10th Science PBQ Chapter 1 to 16

Case-based/Passage-based Integrated Questions 1 CHEMICAL REACTIONS AND EQUATIONS CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Read the given passage and answer the questions Ans. (ii) Formation of crystals by crystallisation is based on passage and related studied concepts. a physical change. We come across many changes around us. Some (d) What happens when hydrogen sulphide gas changes are reversible i.e. no new substance is is passed through aqueous solution of copper formed called physical changes where as some sulphate solution? Write chemical equation. are chemical changes, represented by chemical equation. Chemical equation represents the Ans. Black ppt. of copper (II) sulphide is formed. reactants, products and their physical states. A chemical equation must be balanced so as to CuSO4(aq) + H2S(g) → CuS(s) + H2SO4(aq) satisfy law of conservation of mass. The reactions are classified into combination, decomposition, Copper Hydrogen (Black ppt.) Sulphuric displacement, double displacement, precipitation, redox, combustion, exothermic and endothermic sulphate sulphide Copper (II) acid reactions. Corrosion is a process in which oxidation or redox reaction is involved. Antioxidants are sulphide added to prevent rancidity of food materials. II. Answer the questions on the basis of your understanding of the following paragraph and the related studied concepts. (a) Strong heating of ferrous sulphate leads to Redox reactions involves both oxidation as well formation of a brown solid and few gases. What type of reaction it is? as reduction. If we cut an apple, it turns reddish brown after some time because Fe2+ present in Ans. It is endothermic, decomposition and redox apple gets converted into Fe3+ by loss of electrons. reaction. Oxidation is a process in which loss of electrons 2FeSO4 heat→ Fe2O3 + SO2 + SO3 (b) Balance the following reaction: takes place. Oxidation is carried out with the help Fe + H2O → Fe3O4 + H2 of oxidising agent which can give O2 or remove hydrogen or can gain electrons. Non-metals are Ans. 3Fe + 4H2O → Fe3O4 + 4H2 good oxidising agents, KMnO4, K2Cr2O7 are (c) In which of the following chemical changes also good oxidising agent in acidic medium. the initial substance remains unchanged? Combustion is oxidation reaction. Reduction involve gain of electrons. Reducing agent can add H2 or remove O2 or can lose electrons. Metals are good reducing agents. Reducing agents are used in extraction of metals. (i) Curdling of milk (a) Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) Name the oxidising and reducing agent in the (ii) Formation of crystals by crystallisation above reaction. (iii) Fermentation of grapes A ns. Fe2O3 is oxidising agent, CO is reducing agent. (iv) Digestion of food

Case-based/Passage-based Integrated Questions 509 (b) H2S(g) + Cl2(g) → 2HCl(g) + S(g) The same volume, in excess, of dilute HCl is Name the substances which are getting added to each flask. Loss of mass is determined in each flask with the help of electronic balances oxidising and reduced. and graphs are plotted as shown in diagram. Ans. H2S is getting oxidised to S and Cl2 is getting (a) Why do the three flasks and their content lose reduced to HCl. mass? (c) Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g) A ns. CO2 gas is formed in the reaction which escapes Why is Mg acting as reducing agent and H+ and causes loss in mass. ions are oxidising agent. CaCO3(s) + 2HCl(dil.) → CaCl2(aq) + H2O(l) + CO2(g) Ans. It is because Mg is losing 2 electrons to form Mg2+ where as 2H+ are gaining 2 electrons to (b) How do rate of reaction change with time? form H2(g). (i) Decrease with time (d) Cr2O3 + 2Al → Al2O3 + 2Cr (ii) Increase with time What are types of above reaction? (iii) Does not change (iv) First increase, then decrease Ans. It is redox as well as displacement reaction. Ans. (i) It decreases with time. (c) In which flask reaction is fastest. III. Study the given graph and paragraph given below and answer the questions based on graph and (i) G related studied concepts. (ii) E (iii) F 0 (iv) All have equal Ans. (i) G, because small lumps of CaCO3 react 0.2 0.4 faster. (d) If we use powdered CaCO3, will the reaction 0.6 'E' 0.8 'F' be faster or slower than 'G', why? Loss of mass 1.0 'G' in g 1.2 Ans. It will be faster than 'G' because powdered 1.4 CaCO3 has more surface area, greater the surface 1.6 area, more will be rate of reaction. 1.8 2.0 (e) After how long reaction stops? 2.2 A ns. After 100 seconds the reaction stops. 20 40 60 80 100 120 140 160 180 Time in s (f) Why does reaction stop? Three samples of calcium carbonate are placed Ans. It is because calcium carbonate has been used in the flask for an investigation. up. In flask 'E' 5g of CaCO3 placed in large lumps. (g) What name is given to the reaction if content In flask 'F' 5g of CaCO3 placed in medium size of reaction mixture become warm? lumps. A ns. Exothermic reaction. In flask 'G' 5g of CaCO3 placed in small lumps. (h) Suggest how sodium metal be stored. Ans. It should be stored in kerosene oil. IV. The metal sodium reacts with air and water. A student reacted sodium with water and measured the volume of gas at intervals of 30 seconds. The results are shown below: Time/s 0 30 60 90 120 150 180 Volume/cm3 0 40 60 74 86 96 140

510 Together with® Science—10 (a) At what time rate of reaction was fastest? (d) What will be colour of universal indicator, when added to solution formed. What does A ns. 30 seconds. it show? (b) Name the gas liberated in the above reaction. A ns. It will be bluish violet in colour. It shows the Write the reaction involved. solution is strongly basic (alkaline). A ns. H2 gas is liberated. (e) Which ions are responsible for change in 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) colour of universal indicator? (c) How will you test this gas? Ans. OH– formed from NaOH. Ans. Bring a burning matchstick near the flask, the gas will burn with 'pop' sound confirming it is (f) What will be colour of phenolphthalein in the H2 gas. solution formed? A ns. Pink.

2 ACIDS, BASES AND SALTS CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Read the given passage and answer the questions (d) Sulphuric acid reacts with milk of magnesia, based on passage and related studied concepts. the salt formed is Salts are formed by reactions of acids and (i) MgSO4 bases, strong acids react with strong bases to form neutral salt. Weak acids react with strong (ii) Mg(HSO4)2 bases to form basic salts whose aqueous solution turned red litmus blue, phenolphthalein pink and (iii) MgSO3 universal indicator blue. Acidic salts are formed by strong acids and weak bases. (iv) Mg(HSO3)2 Ans. (i) Mg(OH)2 + H2SO4 → MgSO4 + 2H2O Milk of Magnesium Na2CO3 and NaHCO3 are salts of NaOH (strong magnesia sulphate base) and H2CO3 (Carbonic acid) weak acid and are basic in nature. Electrolysis of brine solution II. Answer the questions based on the paragraph gives caustic soda (NaOH), H2 gas and Cl2. given below and the related studied concepts. Bleaching powder (CaOCl2) is prepared when slaked lime reacts with dry chlorine gas used The sour and bitter taste of food is due to acids as disinfectant, washing soda is used to remove and bases, respectively present in them. If some permanent hardness of water. Crystalline salts person is suffering from a problem of acidity after are hydrated and lose water of crystallisation overeating, we give baking soda solution (ENO) on heating, may change colour and become to the person to give relief. Vinegar contains amorphous (powdery). Gypsum on heating at acetic acid, sour milk (curd) contains lactic acid, 373K gives Plaster of Paris, used in making chalk, lemon contains citric acid where as nettle sting plastering fractured bones. NaHCO3 is baking contains methanoic acid. Bitter gourd, cucumber, soda used in making crisp pakora and as antacid. fenugreek are bitter in taste due to presence of bases in them. (a) Write chemical formula of Plaster of Paris. (a) A sample of ammonium sulphate is warmed with aqueous sodium hydroxide. The gas A ns. CaSO4. 1 H2O produced 2 (i) ignites with a pop (b) What is baking powder? (ii) relights a glowing splint A ns. It is mixture of NaHCO3 and tartaric acid. (c) A visually challenged student has to perform (iii) turns damp red litmus paper blue the presence of acidic salt in given solution. (iv) turns lime water milky The acid base indicator prepared by him will be A ns. (iii) because ammonia is basic in nature. NH3 + H2O → NH4+ + OH– (i) Blue litmus (b) Bitter gourd is (ii) Clove oil (i) Acidic (ii) Alkaline (iii) Red cabbage extract (iii) Neutral (iv) Amphoteric (iv) Hibiscus extract A ns. (ii) It is alkaline in nature that is why it is bitter. A ns. (ii) Clove oil

512 Together with® Science—10 (c) Observe the table which shows different Which of them is strongly basic? colour produced by universal indicator in A, B, C, and D. (i) A (ii) B (iii) C (iv) D Solution Colour of universal Ans. (iv) 'D' is strongly alkaline (basic). indicator A Blue (d) Why is slaked lime added to soil? B Green C Red Ans. Most plants need a soil pH is 6.5 to 7.5 to grow D Violet well. If the soil is too acidic then slaked lime is added to neutralise the acid in soil so as to make nearly neutral. III. Lime is an alkaline substance. The figure shows some of the properties of a calcium compound 'X'. The letters are not chemical symbols of substances. Answer the questions that follow: A colourless compound 'X' heat heat Mix Lime water strongly Gas 'P' with lime turns milky White solid 'Y' water Dissolves in water Colourless aqueous Add universal Blue colour solution 'Z' Indicator (a) Identify 'X' and 'Y'. (e) Write reaction of lime water with 'P'. A ns. 'X' is CaCO3 'Y' is CaO. A ns. Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l) (b) Write the chemical reaction and identify 'P'. Lime water (White ppt) A ns. CaCO3(s)  Hea→t  CaO(s) + CO2(g) IV. Observe the graph drawn between concentration 'X' 'Y' 'P' of H3O+ Vs pH. Observe the graph carefully and answer the questions that follow: Calcium Calcium Carbon dioxide carbonate oxide (c) Identify 'Z' and write reaction of 'Y' to get A 'Z'. Ans. CaO(s) + H2O(l)  → Ca(OH)2(aq) 'Y' 'Z' [H3O+] (Calcium oxide) (Calcium hydroxide) (d) Name an acid which can liberate 'P' from B 'X'? Ans. dil. HCl (Hydrochloric acid). pH

Case-based/Passage-based Integrated Questions 513 (a) What does this graph show? (e) 'B' will be strongly or weakly basic? Ans. As the conc. of [H3O+] decreases, pH of solution A ns. 'B' will be strongly basic because it has highest increases. pH. (b) If pH of solution is 7, what will be colour of (f) What is pH of tooth paste? Why? universal indicator in this solution? Ans. It is more than 7 because it has CaCO3 which A ns. Green. is basic in nature. (c) Does base also contain [H3O+]? If yes, then (g) What will be the colour of universal indicator how are they basic? in NH4Cl solution and why? Ans. Yes, base also contain H3O+, but still they are A ns. It will become orange because NH4Cl is acidic basic because OH– are more than [H3O+]. salt, salt of weak base NH4OH and strong acid HCl. (d) 'A' will be strongly acidic or basic? Why? Ans. 'A' will be strongly acidic because it has lowest pH.

3 METALS AND NON-METALS CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Read the following passage and answer the Ans. X Y2, Ionic compound. X2 Y1 X(2, 8, 2), Y(2, questions that follow based on passage and related studied concepts. 8, 7) XY2 Elements are classified into metals, non- (c) ZnCO3 D→ ZnO + CO2. This process metals and metalloids. Metals are lustrous, is called malleable, ductile and good conductors of heat and electricity, mostly solids, form (i) Roasting (ii) Calcination positive ions and basic oxides. Non-metals are non-lustrous, brittle, exist as soilds, liquids and (iii) Smelting (iv) Reduction gases, non-conductor of heat and electricity, form negative ions and acidic oxides mostly. A ns. (ii) Calcination Some metals form amphoteric oxides and some non-metals form neutral oxides. A more reactive (d) What happens when zinc metal is added metal can displace less reactive metal from its salt solution. Some less reactive metals occur in to Iron (II) sulphate solution? Write the free state. Most of metals occur in combined state in form of ores. Carbonates ores are converted chemical equation. into oxides by calcination and sulphide ores are roasted in presence of oxygen to form oxides. A ns. The pale green colour changes to colourless and Oxides are reduced with suitable reducing agent to get free metal. Metals of middle reactivity series black Fe metal gets deposited. are obtained from their oxides by reduction with Al, Mg. Most reactive metals are obtained by Zn(s) + FeSO4(aq) → ZnSO4(aq) + Fe(s) electrolytic reduction of their molten ores. Impure metals are refined by suitable methods. Metals II. Read the given passage and answer the questions form ionic compounds with non-metals. Ionic based on the passage and related studied concepts. compounds are soluble in water, high melting solids, conduct electricity in molten state and in Pure metals are usually too soft and weak for aqueous solution. most uses. In pure metals the atoms are arranged orderly in layers. When force is applies to the (a) State the common characteristic of the metal, the layers of metal atoms can slide over following elements: one another. B, Si, Ge and As To improve the strength and hardness of metals, atoms of another element can be added usually A ns. These are metalloids, i.e., resemble with metals in small amounts which prevents atoms of the as well as non-metals. metal from sliding over one another, making the metals stronger and harder and less likely to get (b) An element 'X' with atomic number 12 reacts its shape distorted. The final product is an alloy with 'Y' with atomic number 17. What is of metal, e.g. ornaments are made up of 22 carat formula and nature of compound formed? gold in which copper is added to gold. Alloy is a homogeneous mixture of two or more metals. One of them can be non-metal also, e.g., steel is an alloy of Fe and carbon. Alloys are made so as to improve properties of metals. Amalgam is alloy of metal with mercury.

Case-based/Passage-based Integrated Questions 515 (a) What is compostion of stainless steel? What A ns. (iv) All of these are obtained by electrolytic is its advantage? reduction of their molten ores because these are highly reactive and good reducing Ans. It contains Fe + Cr + Ni + C. It does not get agent themselves, so cannot be obtained rusted. by chemical reduction. (b) What is solder? What is its use and why? (c) What happens when Zn is added to CuSO4 solution? Give reason. Ans. It contains lead and tin. It is used for soldering because its melting point is low. A ns. The blue colour solution will change to colourless and reddish brown copper metal will deposited (c) What is advantage of Sodium amalgam over because Zinc is more reactive than Cu. sodium metal? Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s) Ans. Sodium amalgam has less reactivity than sodium (d) Can we store CuSO4 in silver container? Give and more reactivity than mercury, used as reducing agent. reasons. (d) How much gold is present in 22 carat gold? Ans. Yes, because Ag is less reactive than copper, A ns. It contains 22 ×100 = 91.6 % gold and therefore, no reaction will take place. Ag cannot displace copper from CuSO4(aq) solution. 24 remaining copper. IV. The following table gives melting point of some metals. Study the table and answer the questions III. The activity series of metals is shown in the related to table and related studied concepts. box. Study this table carefully and answer the questions based on this series and related studied Metals Melting Point concepts. Na 98°C Reactivity Series K Ag 961.8°C Na Cu 1085°C Ca Al 660.3°C Mg Zn 419.5°C Al Au 1064°C Zn Sn 231.9°C Fe Hg –38.83°C Pb (a) How is sodium and mercury metals are refined and why? H A ns. They are refined by distillation because they Cu have low melting and boiling points. Ag (b) How is copper metal refined? Ans. Electrolytic refining. Au (c) In electrolytic refining, what are anode and (a) Which of the metal is most reactive? cathode made up of? A ns. Anode is made up of impure metal and cathode (i) Al (ii) Mg is made up of pure metal. (iii) Na (iv) K (d) Why is cryolite added to purified bauxite Ans. (iv) K is most reactive. before electrolytic reduction? A ns. It is done so as to reduce melting point of alumina (b) Which metal can be obtained by electrolytic reduction of their molten ores? and increase its electrical conductivity. (i) Na (ii) K (iii) Al (iv) All of these

4 CARBON AND ITS COMPOUNDS CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Read the given passage and answer the questions (d) What happens when ethanol reacts with based on passage and related studied concepts. sodium metal? Write the chemical reaction. Carbon has four valence electrons. It cannot lose or gain four electrons. It can share four Ans. Hydrogen gas is formed. electrons easily. It forms large number of covalent compounds due to property of catenation and 2C2H5OH + 2Na → 2C2H5ONa + H2 tetra valency. Carbon has three crystalline allotropes-diamond, graphite and fullerene Ethanol Sodium ethoxide which differ in physical properties. Alkanes are saturated hydrocarbons, undergo combustion II. Read the given passage and answer the questions and substitution reactions. Alkenes and alkynes that follow: are unsaturated hydrocarbons undergo addition reactions. Ethanol on dehydration with conc. Alcohols form a homologous series with general H2SO4 at 443K gives ethene. Hydrogenation formula CnH2n+1 — OH and hydroxyl (—OH) of vegetable oils in presence of nickel forms group as functional group. Alcohols are colourless vegetable ghee. Alcohol react with carboxylic liquids, boiling points higher than hydrocarbons, acid in presence of conc. H2SO4 to form esters, soluble in water. Lower alcohols have specific pleasant fruity smelling compounds. Alcohol and smell and burning taste. Their boiling point carboxylic acids react with Na metal to liberate increases with increase in molecular weight but hydrogen. Acetic acid reacts with NaHCO3 and solubility in water decrease. Methanol is called Na2CO3 to give CO2 which turns lime water milky. wood spirit used as disinfectant. Ethanol is Esters on heating with NaOH to give sodium commonly called alcohol and is used in alcoholic salt of acid and alcohol. Soaps are prepared by drinks. It is good solvent, used in medicines, cough saponification of fat or oil with NaOH. Detergents syrups, tonics. Consumption of alcohol leads to are more effective and work well with hard water loss of muscular and nervous control. Intake of but some of them are non-biodegradable. small amount of pure alcohol can be fatal and long term consumption of alcoholic drinks cause many (a) Why are covalent compounds poor conductors health problems and ruin family life. Drinking of electricity? methanol may lead to blindness and even death. A ns. It is because they do not form ions in aqueous (a) The formula of butanol is C4H9OH. The next solution. higher homologous series of alcohol is (b) A compound 'X' on combustion gives a yellow (i) C3H7OH (ii) C2H5OH flame with lots of smoke. What inference (iii) C5H11OH (iv) C6H13OH would you draw from this statement? Ans. (iii) C5H11OH is pentanol. (b) Which of the following will give C2H5OH on Ans. 'X' is unsaturated hydrocarbon. addition of H2O in presence of H2SO4? (c) State the role of alkaline KMnO4 in conversion (i) C2H6 (ii) CH2==CH2 of alcohol to corresponding carboxylic acid. (iii) HC≡≡CH (iv) CH4 Ans. (ii) CH2==CH2 + H2O H2SO→4 CH3CH2OH A ns. It acts as oxidising agent.

Case-based/Passage-based Integrated Questions 517 (c) What is absolute alcohol? Ans. Acetic acid formed. Ans. Pure alcohol (100%) is called absolute alcohol. CH3CH2OH + 2(O) KMnO4/KOH→ CH3COOH (d) What is tincture of iodine? Give its use. A ns. Iodine dissolved in alcohol is called tincture of + H2O (h) How are ester formed? Give One of their iodine, it is used as an antiseptic. (e) Why is alcohol better fuel than hydrocarbons? use. A ns. It is because it creates less pollution and burns A ns. They are formed by reaction of carboxylic acid completely. with ethanol in presence of conc. H2SO4. Esters C2H5 – OH + 3O2 → 2CO2(g) + 3H2O are used in food flavouring and used in making perfumes. III. Observe the table of boiling points of alcohols and carboxylic acids. Study this table and answer the CH3COOH(l) + C2H5OH(l) Conc.DH2SO4→ questions related to studied concepts. CH3COOC2H5(l) + H2O(l) Compound Boiling point IV. Read the given passage and answer the questions 1. Methanol 64°C that follow: 2. Ethanol 78°C 3. Propanol 97°C Soaps and detergents are cleansing agents. Soaps 4. Butanol 117°C are sodium or potassium salts of higher fatty 5. Methanoic acid 101°C acids. Detergents are sodium or potassium salts 6. Ethanoic acid 118°C of sulphonic acids. Soaps do not work well with 7. Propanoic acid 141°C hard water where as detergents work well with 8. Butanoic acid 164°C hard water. Soaps are biodegradable and do not create water pollution. Some detergents create (a) Why do acids have higher boiling points than water pollution. alcohol? (a) Give difference in functional group of soaps Ans. It is because acids have stronger forces of and detergent. attraction than alcohols. A ns. —COONa in soaps —SO3Na or SO4Na in (b) Why does ethanol have higher boiling point detergents. than CH3OH? (b) Name one useful product formed in Ans. C2H5OH has higher molar mass, more van der saponification of oil or fat to prepare soap. Waals' forces of attraction than CH3OH. Ans. Glycerol. (c) What is vinegar? (c) Do soaps and detergents form micelles in Ans. 5 to 8% solution of acetic acid in water is called ethanol? vinegar. A ns. No, ethanol attracts both hydrophilic as well as (d) What is glacial acetic acid? hydrophobic part. A ns. Pure acetic acid is called glacial acetic acid. (d) What type of detergents are not biodegradable? (e) Which acid is present in red ants sting? Ans. Detergents with branched chain are not biodegradable. A ns. Methanoic acid. (e) Give one example of soap. (f) Which acid is present in Rancid butter? A ns. Sodium stearate. A ns. Butanoic acid (Butyric acid). (f) Give name of detergent used in tooth paste. (g) What happens when 5% alkaline solution of KMnO4 is added to ethanol? A ns. Sodium lauryl sulphate. (g) Why do soaps not work well in hard water? Ans. Ca2+ and Mg2+ salts of fatty acids are insoluble, i.e., scum is formed and soap goes waste.

5 PERIODIC CLASSIFICATION OF ELEMENTS CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Read the given passage and answer the questions (e) Name the lightest metal in the periodic table. that follow: Ans. Lithium (d = 0.53 g cm–3). Elements are arranged in Modern Periodic table II. Study the graphs shown in the diagram and in increasing order of their atomic numbers. answer the questions that follow: Metals are on left hand side and middle of periodic table mainly and non-metals are on right 300 Group 1 Cs (262) hand side. A zig-zag diagonal line divides metals Rb (244) and non-metals. Elements near zig-zag line are called metalloids. Elements of same group have 250 K (23) same number of valence electrons but different number of shells. Elements of same period have Atomic 200 Na (186) different number of valence electrons but same Radius 150 number of shells. Elements in the middle of Li (152) I (133) periodic table are called transition metals. Group 17 Br (114) (a) Which one of the following statement is 100 Cl (99) correct. 50 F (72) (i) All group contain both metal and non- metals. 10 20 30 40 50 Atomic Number (ii) In group 17, reactivity decreases down the group. (a) How does atomic size vary down the group and why? (iii) In group 1, reactivity decreases down the group. A ns. Atomic size goes on increasing down the group because number of shells goes on increasing. (iv) Atoms of same group have same number of electrons. (b) Which group elements have largest atomic size in respective periods? Ans. (ii) In group 17, reactivity decreases down the group. Ans. Group 1. (b) Which of the following is correct formula of (c) Which group elements are smallest in size in hydrides of phosphorus? respective periods? (i) PH2 (ii) PH3 A ns. Group 17. (iii) PH5 (iv) PH4 A ns. (ii) PH3 is correct formula. (d) How does atomic size vary along a period (c) Why group 1 elements are soft and have low and why? melting and boiling points? A ns. Atomic size decreases along a period from left to right because effective nuclear charge increases A ns. It is because, they have larger size, weak metallic as number of shells remain the same. bond. (e) Identify two metals, two non-metals and one (d) Name two elements have density less than metalloid in 3rd period? one. Ans. Na and Mg are metals, 'Si' is metalloid, 'P' and A ns. Sodium and potassium. 'S' are non-metals.

Case-based/Passage-based Integrated Questions 519 III. Observe the data given in the table and answer the questions based on table and related concepts. Ionisation energy is energy required to remove an electron from an isolated gaseous atom. It helps to decide tendency to lose electrons. Electronegativity depends upon tendency to attack shared pair of electron towards itself. Melting point of elements depend upon intermolecular forces of attraction and physical state. Element Ionisation energy Element Melting point Colour Electronegativity Li –220°C Yellow 4.0 Na 520 kJ mol–1 F2 –101°C Yellowish greeen 3.2 K Cl2 –7°C Reddish brown 2.9 Rb 496 kJ mol–1 Br2 114°C Violet 2.6 Cs 419 kJ mol–1 I2 403 kJ mol–1 374 kJ mol–1 (a) What happens to tendency to lose electrons (f) Name two elements which are gases in graph down the group? Why? 17. A ns. Tendency to lose electrons increases down the A ns. Fluorine and chlorine. group because atomic size increases, effective nuclear charge decreases. (g) Name group 17 elements which are liquid and solid. (b) What happens to tendency to gain electron down the group? Why? A ns. Br2 is liquid and I2 is solid. (h) What happens when Cl2 is passed through A ns. Tendency to gain electron decrease down the group because atomic size increases, effective KI solution? nuclear charge decreases. Ans. Cl2 displace iodine from KI solution because (c) Arrange group 1 elements in the increasing Cl2 is more reactive than I2. order of reactivity. 2KI(aq) + Cl2(g) → 2KCl(aq) + I2(aq) Ans. Li < Na < K < Rb < Cs (i) What happens to metallic character down the (d) Arrange group 17 elements in increasing order group? of reactivity. A ns. Metallic character goes on increasing down the A ns. I < Br < Cl < F. group. (e) What will happen if F2 gas is passed through (j) Name one metal and one metalloid in second NaCl solution? period. Ans. NaF and Cl2 will be formed. A ns. Lithium and Beryllium are metals, Boron is 2NaCl(aq) + F2(g) → 2NaF(aq) + Cl2(g) metalloid.

6 LIFE PROCESSES CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your (a) What are the functions of kidneys in human understanding of the following paragraph and being? Give any two functions. related studied concepts. Ans. Functions of kidneys Chronic kidney disease, or CKD, causes more deaths than breast cancer or prostate cancer. It (i) It removes the poisonous substances from is the  under-recognized public health crisis. It blood affects an estimated 37 million people in the U.S. and approximately 90% of those with CKD don’t (ii) It regulates water balance of the blood even know they have it.  1 in 3 American adults is at risk for CKD. CKD is more common in women (b) State two main causes of Chronic Kidney (15%) than men (12%). CKD is the 9th leading diseases. cause of death in the U.S.   Chronic kidney disease (CKD) means kidneys are damaged and Ans. (i) Diabetes losing their ability to keep you healthy. In the early stages of the disease, most people do not (ii) High blood pressure have symptoms. But as CKD gets worse, wastes can build up in blood and one gets sick. One (c) What is artificial kidney? may develop other problems like high blood pressure, anemia, weak bones, poor nutritional Ans. It is a device to remove the nitrogenous waste health, and nerve damage. Because kidneys are products from the blood of a person with vital to so many of the body’s functions, CKD damaged kidneys with the process of dialysis. also increases risk of having heart and blood vessel disease. While these problems may happen (d) Name the basic filtration unit of kidneys. slowly and without symptoms, they can lead to kidneys failure, which can appear without A ns. Nephron warning. Once kidneys fail, dialysis or a kidney transplant is needed to stay alive. This stage II. Answer the questions on the basis of your of CKD is known as kidney failure, end-stage understanding of the following paragraph and kidney disease (ESKD). The two main causes of related studied concepts. CKD are diabetes and high blood pressure. These two conditions were responsible for nearly 75% Respiratory disease causes an immense of kidney failure cases between 2014–2016:  45% worldwide health burden. It is estimated that of new ESKD patients had a primary diagnosis of 235 million people suffer from asthma, more diabetes, the leading cause of ESKD, while 29% than 200 million people have chronic obstructive of new ESKD patients had a primary diagnosis of pulmonary disease (COPD), 65 million endure hypertension, the second leading cause of ESKD. moderate-to-severe COPD , more than 100 million adult population experience sleep disordered breathing, 8.7 million people develop tuberculosis (TB) annually , millions live with pulmonary hypertension and more than 50 million people struggle with occupational lung diseases. At least 2 billion people are exposed to the toxic effects of biomass fuel consumption, 1 billion are exposed to outdoor air pollution and 1 billion are exposed to tobacco smoke. Each year, 4 million people die prematurely from chronic respiratory disease. Infants and young

Case-based/Passage-based Integrated Questions 521 children are particularly susceptible. Nine million (b) How are lungs designed to maximize exchange children under 5 years of age die annually and of gases? lung diseases are the most common causes of these deaths. Pneumonia is the world’s leading Ans. In human being, to maximize the area for killer of young children. Asthma is the most exchange of gases, inner surface of lungs has common chronic disease, affecting about 14% smaller tubes that terminate into balloon like of children globally and is still rising. COPD is structures called alveoli. The walls of alveoli the fourth leading cause of death worldwide and have extensive network of blood vessels. the numbers are growing. The most common lethal cancer in the world is lung cancer, which (c) ‘While breathing cycle is rhythmic, exchange kills more than 1.4 million people each year, of gases is a continuous process.’ Justify. and the numbers are growing. Respiratory tract infections caused by influenza kill 250 000–500 Ans. Even though the breathing cycle is rhythmic, 000 people and cost 71–167 billion US dollars the lungs always contain a residual volume of annually. Respiratory infections are ranked as air so that absorption of oxygen and release the greatest single contributor to the overall of carbon dioxide becomes continuous. burden of disease in the world. (d) Therespiratorydisorderinwhichinflammation (a) Write one difference between respiration in of air sacs in lungs takes place is called: plants and respiration in animals. (i) Pneumonia Ans. Respiration in Respiration in Plants animals (ii) Asthama (iii) Bronchitis (iv) None of these Ans. (i) Pneumonia Plants donot have Animals have respi- respiratory system. ratory system.

7 CONTROL AND COORDINATION CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your (c) What are the functions of midbrain? understanding of the following paragraph and Ans. Midbrain controls reflex movements of the related studied concepts. head, neck and trunk in response to visual and Spinal cord reflexes are simple behaviors produced auditory stimuli. by central nervous system (CNS) pathways (d) Which part of the brain is used to think? that lie entirely within the spinal cord. The A ns. Fore-brain sensory afferent fibers that evoke these reflexes enter the spinal cord and activate spinal motor II. Answer the questions on the basis of your neurons directly or through a chain of one or more understanding of the following paragraph and spinal interneurons. Although these pathways are related studied concepts. entirely spinal, they are affected by descending pathways from the brain, either directly or Parkinson (PD) is a type of movement disorder through other spinal interneurons. Through that can affect the ability to perform common, these descending pathways, the brain exerts both daily activities. Although PD is associated with short-term and long-term influence over spinal a wide range of symptoms, there are features cord reflex function. In the short term, the brain of PD that most people with the condition rapidly adjusts spinal reflexes to suit the needs will experience. These symptoms are typically of different tasks (e.g., standing vs. walking vs. divided into those that affect movement (motor running). In the long term, it gradually shapes symptoms) and those that do not (non-motor spinal reflexes during development, during skill symptoms). The most common motor symptoms acquisition later in life, and in response to CNS of PD are tremor (a form of rhythmic shaking), trauma and disease. The long-term changes that stiffness or rigidity of the muscles, and slowness the brain induces in spinal cord reflexes involve of movement. A person with PD may also have activity-dependent plasticity in the spinal cord trouble with posture, balance, coordination, itself. and walking. Common non-motor symptoms of PD include sleep problems, constipation, (a) State one advantage of reflex action? anxiety, depression, and fatigue, among others. A ns. Advantage of Reflex Action is that it enables the It is important to note that, although there are common symptoms of PD, they can vary greatly body to give quick response to harmful stimuli from person to person. Most people who develop and thus protects our body. the symptoms of PD do so sometime after the (b) What is Central Nervous System? age of 50, but PD can affect younger persons as Ans. The Central Nervous System consists of brain well. There are an estimated 1 million Americans and the spinal cord. Both brain and spinal cord living with PD and more than 10 million people are protected by skeleton- brain by the cranium worldwide. and the spinal cord by the vertebral column.

Case-based/Passage-based Integrated Questions 523 (a) What are endocrine glands? (c) Reflex action is controlled by (i) brain Ans. Endocrine glands are structures or group of cells (ii) spinal cord which manufacture hormones and secretes them (iii) hypothalamus directly into the bloodstream to act at distant (iv) pancreas sites in the body known as target cells. Ans. (i) spinal cord (d) Name the hormone synthesised at the shoot (b) What hormone is released by hypothalamus gland? What is the function of this hormone? tip of plants Ans. Auxin is synthesised at shoot tip of plants. Ans. Hypothalamus gland produces ‘releasing hormone’. It regulates secretion of hormones from pituitary gland.

8 HOW DO ORGANISMS REPRODUCE? CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your (c) How can people be made aware about AIDS? understanding of the following paragraph and related studied concepts. Ans. People can be made aware about AIDS by conducting awareness camp, organizing street The human immunodeficiency virus (HIV) drama, newspaper advertisement, hoarding etc. targets the immune system and weakens people’s defence systems against infections. As the virus (d) What are the symptoms of HIV infection? destroys and impairs the function of immune cells, infected individuals gradually become Ans. Swollen lymph nodes, fever and tiredness are immunodeficient. Immunodeficiency results some common symptoms of HIV infection,but in increased susceptibility to a wide range of a blood test is the only way to know for sure if infections, cancers and other diseases that people a person have HIV infection. with healthy immune systems can fight off. II. Answer the questions on the basis of your The most advanced stage of HIV infection is understanding of the following paragraph and acquired immunodeficiency syndrome (AIDS), related studied concepts. which can take from 2 to 15 years to develop if not treated, depending on the individual. The The availability of food is an essential situation symptoms of HIV vary depending on the stage for food production. India is more or less of infection. Though people living with HIV tend self-sufficient in cereals but insufficient in to be most infectious in the first few months pulses and oilseeds. Due to the changes in after being infected, many are unaware of their consumption patterns, demand for fruits, status until the later stages. In the first few weeks vegetables, dairy, meat, poultry and fisheries has after initial infection people may experience no been increasing. Hence, there is a need to raise symptoms or an influenza-like illness including crop diversification and improve allied activities. fever, headache, rash or sore throat. In this situation, plant tissue culture offers remarkable opportunities in in-vitro propagations, (a) Name two modes of transmission of AIDS. plant quality improvement and production of Ans. Two modes of transmission of AIDS are plants with desirable agronomical quality and (i) By having sexual contact with an infected quantity. It’s now possible to develop virus-free plant regeneration, herbicide resistance, salinity person. tolerance, disease resistance, incorporation of (ii) By transmission of blood from an infected high protein content and genetically engineered plants for desirable traits. Micropropagated person. plant cells and tissues have been widely used for (b) List two preventive measure to get infected the production of secondary metabolites, which are the rich source of many pharmaceutical and by AIDS. industrial products. Crop plants play a major Ans. (i) Using condom during sexual contact. role in the human nutrition and health by (ii) Testing of blood before transfusion. providing carbohydrates, proteins, fats, minerals, antioxidants, vitamins, phytoconstituents and dietary fibres.

Case-based/Passage-based Integrated Questions 525 (a) What is tissue culture? (c) Write one difference between Budding and Fission. Ans. Tissue culture is the production and propagation of new plants from isolated plant cells or small Ans. Budding Fission pieces of plant tissue in a synthetic medium of culture solution. An overgrowth called The parent organism (b) Mention one advantage of vegetative bud appears on the divides into two or propagation. parent organism. more. Ans. It results in propagation of those plants which donot produce viable seeds or produce seeds (d) Which of the following plants can be with prolonged period of dormancy. reproduce by vegetative propagation: (i) rose (ii) banana (iii) jasmine (iv) All of these A ns. (iv) All of these

9 HEREDITY AND EVOLUTION CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your Every year, new words get added to dictionaries understanding of the following paragraph and around the world, while other words slip from related studied concepts. our lexicon. A recent study looked at the rate at which languages pick up or lose vocabulary. Within minutes of a baby’s birth, people start The researchers found that, similar to biological remarking about who this new baby resembles. evolution, languages evolve at different speeds ‘Oh, he has his daddy’s chin!’ or ‘She’s got depending on the size of the population that her mother’s eyes!’ but from where exactly do speaks them. To tease out the relationship these similarities arise? Every individual has between population size and evolution, the 46 chromosomes, 23 chromosomes from each researchers--a group of linguists and evolutionary parent. The chromosomes are composed of biologists from the Australia National University- deoxyribonucleic acid or DNA that is tightly -compared 20 different Polynesian languages. bundled. Now, certain segments of the DNA Polynesian languages are ideal because they›re which are responsible for different traits in an relatively new; Polynesia was settled relatively individual are termed genes. Each chromosome recently in human history. The languages contains over 20,000 genes. There is a lot of diversified quickly across different islands, and copying that has to take place to pass all these the relationships between the languages have genes on from parents to a newly growing child. been thoroughly studied in the past. This way, Understandably sometimes mistakes are made in the researchers could compare languages with the copying process. different population sizes and see where the vocabularies differ. (a) What is a Gene? The team compared pairs of languages that Ans. Gene is a part of chromosome which controls the share a recent common ancestor. These are called appearance of a set of hereditary characteristics. “sister” languages. By seeing how much each sister language changed since the two island populations (b) What is the importance of variation? separated, the researchers found that languages with larger populations gained new vocabulary Ans. Variation enables organisms to adapt themselves faster than smaller languages. At the same time, in the changing environment. languages with smaller populations tended to lose vocabulary faster than those with a larger (c) Why no two individuals are absolutely similar population. These changes occurred more often in a population? than the scientists predicted would happen by chance alone. The results are similar to biological Ans. This is due to the variations which take place evolution, where smaller populations lose genetic during DNA copying. diversity rapidly, while larger populations have more opportunities to develop new mutations that (d) Give any two examples of human traits which generate more diversity. show variation. Ans. (i) Colour of eye (ii) Height II. Answer the questions on the basis of your understanding of the following paragraph and related studied concepts.

Case-based/Passage-based Integrated Questions 527 (a) What is organic evolution? (c) What is speciation ? Ans. The process of evolution of reproductive Ans. Evolution is the sequence of gradual change which take place in the primitive organisms over isolation among once interbreeding population. million of years and new species are produced. (d) The weight of a particular species is an Since the evolution is of living organisms, so it is called organic evolution. example of : (i) Continuous variation (b) Can evolution be equated to progress? (ii) Discontinuous variation (iii) Mutation Ans. Evolution cannot be said as progress from lower (iv) None of these forms to higher forms. It seems to have given Ans. (i) Continuous variation rise to more complex body design even while the simpler body designs continue to flourish.

10 LIGHT– REFLECTION AND REFRACTION CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions that follow on the basis of divided by the length of the original object. For your understanding of the following paragraph example, if a 2cm long beetle appears to be 6 cm and the related studied concepts: long when viewed through a magnifying glass, the glass’ magnifying power is 3 (written as “3x”)’ Lenses are objects made of transparent materials Similarly, a 10x lens would make an object look such as glass or clear plastic that has curved 10 times longer. It will also look 10 times wider. surfaces. There are two main kinds of lenses — Diverging lenses and Converging lenses. (a) Explain why you cannot measure the focal Diverging lenses are thicker at their edges than length directly for a diverging lens. in their centres and they make light rays passing through them spread out. Converging lenses are Ans. Measurement of the focal length is not possible thicker in the middle than at their edges and for a diverging lens because diverging lens were the earliest kind of lens made. The earliest diverge the rays and cannot intersect to produce examples of these date back two thousand years. a real image. They have been used in spectacles to help people with poor vision see better since at least the tenth (b) What happens to the focal length of the century. convex lens when it is cut horizontally? object at ∞ Ans. When the convex lens cut horizontally, the radius of curvature of both curved surface will remain F same. Accordingly, there will be no change in its focal length. Image at F (c) What kind of image is formed by a concave These days, as well as being used in spectacles lens irrespective of the position of the object? converging lenses are used in many other devices. Magnifying glasses, microscopes and some types Ans. Virtual, erect and diminished of telescopes use converging lenses to make small things appear much larger or to make distant (d) When seen through a 5x magnifying glass, a objects appear much closer. Converging lenses small leaf appears to have an area of 25mm2. magnify by bending the rays of light that pass What is the actual area of the leaf? through them to meet at a point. This point is called the focus. The thicker that a converging Ans. 1mm2, as each side appears five times longer. lens is in its centre, the more it magnifies and the closer the focus is to the lens. II. Answer the questions that follow on the basis of your understanding of the following case and the The magnifying power of a single converging related studied concepts: lens such as that used in a camera or magnifying glass is equal to the length of the enlarged image Shyam participated in a group discussion in his interschool competition on the practical application of light and was very happy to won the award for his school. On that very evening, his father celebrated the day with a family dinner. At a particular moment, Shyam observed in a curve

Case-based/Passage-based Integrated Questions 529 plate, the image of a person’s mobile sitting on (a) State the lens formula. his back side. Person’s mobile was fell off which the person didn’t know about it. Shyam went to Ans. The Lens formula gives the relationship between the person and informed about this. The person was thankful to Shyam. object distance (u), image-distance (v) and the (a) From which side of the plate Shyam observed focal length (f ) is given by this incident? 1 − 1 = 1 Ans. Outward curve v u f (b) The part of the curve plate was acting like (b) Write the serial number of that observation which type of mirror? which is not correct. How did you arrive at Ans. Convex mirror this conclusion? (c) State the nature and size of image formed by this mirror. Ans. Observation at S.No. 6 is not correct. The value, u = – 10 cm, indicates that the object Ans. Virtual, erect and diminished is in between the optical centre and the focus (d) An object is placed at a large distance in front (i.e., less than the focal length) of the lens and of a convex mirror of radius of curvature 40cm. How far is the image behind the hence, the image should be on the same side mirror? as the object. Accordingly, the image distance Ans. The rays coming from an object placed at large should be negative and cannot be positive (+100 distance can be considered as a parallel rays. After reflection from it, they appear to meet at cm) as shown in table. its focus which is 40/2 = 20 cm. (c) Take an appropriate scale to draw ray III. Analyse the following observation table showing diagram for the observation at S. No. 2. variation of image distance (v) with object distance (u) in case of a convex lens and answer Ans. Ray diagram for the observation at S.No. 2 : the questions that follow, without doing any Given: u = – 60 cm; v =+20 cm; f = +15 cm calculations: A F B′ 2F B 2F F O S. Object distance u Image distance v 60 cm A′ No. (cm) (cm) 20 cm 1 – 90 + 18 (d) Under what condition does a biconvex lens of glass having a certain refractive index act 2 – 60 + 20 as a plane glass sheet when immersed in a liquid?    3 – 30 + 30 Ans. When the refractive index of a lens is equal 4 – 20 + 60 to the refractive index of a liquid in which it is immersed, then the focal length of a lens 5 – 18 + 90 becomes infinity and hence it acts as a plane 6 – 10 + 100 glass sheet.

11 HUMAN EYE AND THE COLOURFUL WORLD CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions that follow on the basis of (d) Explain the cause of presbyopia. your understanding of the following case and the related studied concepts: Ans. The power of accommodation of the eye decreases with ageing. It arises due to Two children went to the park with their grandfather. On reaching the park, the children (i) gradual weakening of the ciliary muscles, joined others to play, while their grandfather and after taking three rounds of the park, sat on the chair, took out newspaper from his bag and (ii) diminishing flexibility of the eye lens. began to read with the help of his spectacle. After sometime, he realised that it was too long to see II. Answer the questions that follow on the basis of the children, he looked around, but though he has your understanding of the following paragraph worn spectacle, he couldn’t see anything. He then and the related studied concepts: realised that he had forgotten his other spectacle, which he used to see the faraway places, were left One of the optical refractive defects of the at home. He began calling them by their names, eye is myopia, commonly referred to as short- but due to the large distance, his voice was not sightedness. It is a visual dysfunction that limits reaching the children. Another man sitting beside the ability to see distant objects clearly or without him realised the problem and helped him to reach the aid of glasses. Myopia usually sets in early, the children. affecting school-going children. (a) Name the eye defect with which the Normally, the children do not complained grandfather was suffering from? defective vision and may not even be aware of their problem. They may adjust to poor Ans. Presbyopia vision by strategies such as changing position in the classroom, moving objects closer, and (b) How is it different From Hypermetropia tending to avoid tasks that require more visual (Farsightedness)? concentration. Ans. Presbyopia occurs when your eyes’ lenses lose A study done in Delhi by AIIMS revealed that 1 their elasticity, failing to focus light on the retina, of 6 or 17% of children between the ages of 5 and while hypermetropia develops when the cornea 15 is myopic. These studies have confirmed that becomes abnormally rigid or the shape of the many children are in need of spectacle correction eye is shorter than usual. and in rural India, around 86 per cent of children presented without correction for refractive error. (c) Which type of spectacles should he wear, so as to avoid calling the other? In fact, if current trends continue, half of the world’s population will be nearsighted by the Ans. Bifocal lenses, the upper portion of a bifocal lens year 2050. is concave and its lower portion is convex. The concave lens is used for viewing long distant Myopia is an important health issue in India and objects and the convex lens is used to see nearby is associated with long hours of reading and screen objects and for reading purposes. time with use of computers and video games. An annual eye vision screening should be conducted, and outdoor activities be promoted to prevent the increase of myopia among school children

Case-based/Passage-based Integrated Questions 531 (a) State the two basic cause of myopia. The foundation of modern optics lays in 1672 Ans. This defect may arise due to when Sir Isaac Newton publishes his paper on the bending of light through prism. His experiments (i) excessive curvature of the eye lens, or in bending of light through prisms led, eventually, to the revolutionary discovery of the existence of (ii) elongation of the eyeball. a mixture of distinct coloured rays in white light and, distinguishable when refracted through a (b) What is the condition of ciliary muscles of prism. In his experiment, he set up a prism near the eye when the eye is looking at a distant his window, and projected a beautiful spectrum object? Is the focal length of the eye in this 22 feet onto the far wall. Further, to prove that condition be maximum or minimum? the prism was not colouring the light, he refracted the light back together. Ans. When our eyes see distant objects, the ciliary muscles are in a relaxed position and the focal Prisms are made from transparent materials such length of the eye lens is maximised. as glass, plastic and fluorite and are in different forms and shapes, depending on the application. (c) Based on the data for age specific incidence They are usually categorised based on the shapes of myopia, represented in the graph below, of their bases. at which age, the children suffer maximum myopic visual dysfunction and why? Prism has the capacity to reverse the direction of light by internal reflection and redirect 5 the light at a defined angle. It is mostly used 4.5 in telescopes, periscopes and microscopes, binoculars, and monoculars. Prism spectrometer 4 is used to measure the deviations of light for 3.5 various wavelengths. 3 2.5 2 1.5 1 0.5 0 < 9 yrs. 9 yrs. 10 yrs. 11 yrs. 12 yrs. 13 yrs. 14 yrs. 15 yrs. Ans. The children at the age of 9 years suffer (a) State the property of light that is used by the maximum myopic visual dysfunction because prism to form a spectrum. children in this age group have long hours Ans. Refraction of light of reading and screen time with the use of (b) Which exciting phenomenon is shown by the computers and video games. triangular glass prism? (d) Make a diagram showing the correctness of Ans. The inclined refracting surfaces of triangular myopic defect. glass prism show the phenomenon of dispersion Ans. A concave lens is placed in front of the eye of light, i.e. splitting of incident white light into which forms a virtual image of distant object its component colours : red, orange, yellow, at far point (F) of the myopic eye as shown in green, blue and violet. the figure below: (c) List any two factors on which the angle of deviation through a prism depends. Parallel rays from distant L Retina Ans. The angle of deviation through a prism depends object (at infinity) on (i) angle of prism, FI (ii) angle of incidence and (iii) nature of the material of prism.(any two) Virtual image formed at F III. Answer the questions that follow on the basis of your understanding of the following paragraph and the related studied concepts.

532 Together with® Science—10 and secondary rainbows. Higher order rainbows are never seen since they are weaker than (i) the (d) Suppose you have two glass prisms. One was background sky brightness (ii) the light reflected made of ordinary glass and other one is with from the outside surface of the drops and (iii) flint glass (Given that refractive index of flint the light transmitted through the process with glass is more than that of ordinary glass). no internal reflections. What conclusion can be drawn about bending of light for the given angle of incidence by you (a) What is refraction? after tracing the path of ray of light through both the prism? Ans. The phenomenon of change in the direction of propagation of light rays in the second medium Ans. The bending of light is more in the prism made when it enters obliquely from one transparent of flint glass. medium to another is called refraction of light. IV. Answer the questions that follow on the basis of (b) List two essential conditions for observing a your understanding of the following paragraph rainbow. and the related studied concepts: Ans. Necessary conditions for the formation of a A rainbow is one of the most spectacular natural rainbow. light shows observed in the sky. A number of scientist and mathematician including Aristotle, (i) The presence of water droplets in the Bacon, Theodoric, Descartes, Newton, Young, atmosphere, and Airy and Mie have worked on the explanation of various observations on rainbows. (ii) The sun must be at the back of the observer, i.e. the observer must stand with his back To understand the formation of rainbow one towards the sun. should actually study the refraction, internal reflection dispersion and total deviation of white (c) What is the shape of a rainbow? light by the spherical water drop. Ans. Rainbows are an arc at a constant angle from A rainbow is produced when sunlight falls and the shadow of your head. So the shape is an arc gets diverted to the eyes of the observer due to a along the circumference of a circle. large number of water droplets in the sky on a rainy day. (d) Why the red appears on the top of rainbow? In addition to primary Rainbow there is a Ans. Red has the longest wavelength among the secondary rainbow. It occurs in the same manner visible colours. So it tends to bend the least and as the primary rainbow but due to two internal the angle between the incident light and our line reflections. In nature we can observe only primary of sight for red is approximate 42 degrees. As a result, red appears on the top of the rainbow.

12 ELECTRICITY CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions that follow on the basis of Ans. In AC circuits, because the alternating current is your understanding of the following paragraph constantly changing its magnitude and direction along with related table and the related studied periodically. concepts. (b) As the voltage across a resistor is increased, Georg Simon Ohm (1789-1854) was a German what happens to the resistance of the resistor? mathematician, “The physicist” and a high school teacher. At that time, the resources available to Ans. If you increase the voltage while keeping the him for his research and experiment were: resistance the same, then the current must increase through that resistor to make the (i) The magnetic field surrounded a wire carrying ratio V/I remain same i.e the resistance of the electric current discovery by Oersted in 1520; resistor will remain same. (ii) The electrochemical cell, described by Volta (c) Define 1 Ohm. in 1800; and Ans. The resistance offered by the wire carrying (iii) The thermoelectric effect, discovered by 1 ampere of electric current when 1volt is Seebeck in 1822. applied across its ends. (d) What happens to resistance of a wire if its From these resources and using equipment area of cross-section is decreased? of his own creation, he was able to define Ans. Resistance increases as resistance is inversely the fundamental relationship among voltage, proportional to its area of cross-section. current, and resistance, which represents the true beginning of electrical circuit analysis. II. Study the table related to combination of resistors Now, today in any part of world, most of us and answer the questions that follow on the basis use electricity every day. That electricity is handled in circuits: a closed loop of conductors of your understanding and the related studied travelling from power plants to neighbourhoods to households and back again. That closed loop concepts. uses the three essential parts of a circuit – power supply (or battery), wires, and resistors forms one Circuits consisting of just one battery and one load huge electrical circuit. resistance are very simple to analyse, but they are (a) Why Ohm’s law is generally applied only to direct current (DC) circuits, not alternating not often found in practical applications. Usually, current (AC) circuits. we find circuits where more than two components are connected together in different combinations. These combinations of resistors put the limit on the current that flow through the circuit. After performing the experiments using two different types of circuit arrangements, the following observations were made by them and find the resistance using Ohms law.

534 Together with® Science—10 Resistor Number of Voltmeter Ammeter reading R = V Used Observation reading in in ampere (A) I Volt (V) 0.01 (in ohm) 0.02 R1 (a) 0.01 1.0 (b) 0.02 0.03 1.0 R2 0.04 (a) 0.06 2.0 Ist combination of (b) 0.08 0.01 2.0 R1 and R2 0.02 IInd combination (a) 0.03 3.0 of R1 and R2 (b) 0.06 0.045 3.0 0.09 (a) 0.03 0.66 (b) 0.06 0.66 (a) From observation, which combination represents series and parallel combination of the resistor R1 and R2? Ans. Ist combination of R1 and R2 represents a series combination while IInd combination represents parallel combination of resistors. (b) You will plot V Vs.I for each of the four circuits on one graph. What value should each slope have? (Note: I on X-axis and V on Y-axis) Ans. The slope of each plot of V Vs.I has the same value of resistance of the resistor R as shown in table. (c) Note that the measured currents across each resistor in parallel circuit were not the same. Which resistor had the larger current going through it? Why? Ans. The lower resistor R1 because low resistance making it easier for current to flow through it. This can also be supported mathematically through Ohm’s Law, as V = IR. (d) Do you think the bulbs in the parallel circuit or the series circuit will burn brighter? Ans. In a series circuit, the voltage is distributed among all of the bulbs whereas in parallel circuit the voltage for each bulb is the same as the voltage in the circuit. So, the bulbs in parallel are brighter than bulbs in series. III. Answerthe questions that follow on the basis of your Ans. Copper and aluminium are most frequently understanding of the following paragraph along used as the electrical conductors in electrical with related table and the related studied concepts. cables due to their low resistance/resistivity and excellent conductivity. Electricity requires an electric path to flow and there are many conducting materials used for (c) Write the equation relating power to voltage this purpose. There are non-conducting materials and current, for an electrical resistance. Also, which are used as insulation during working on describe what physical form this dissipated live-lines. energy usually takes. Permanent indoor wiring is responsible for Ans. The equation relating power to voltage and bringing electricity throughout your home. In current, for an electrical resistance is given house wiring of the switches, holders and sockets by P =VI. Energy dissipated by an electrical should be fixed on wooden/sunmica boards and resistance is usually in the form of heat ( H = blocks. Nowadays, there are many semiconducting I2Rt), although sometimes it is also in the form materials which are used to reduce the voltage of light. and also drop the current flow. This will reduce our consumption of electrical energy. (d) Calculate the energy consumed in kWh by 1500 W electric geyser in 3 hrs in a day. (a) In which combination household wiring is done? Ans. Given: P = 1500, W = 1500/1000 = 1.5 kW, t = 3 hrs Ans. Parallel combination Now, E = P × t = 1.5 × 3 = 4.5 kWh (b) Write down the properties of copper and aluminium and about their applications in Total energy consumed = 4.5 kWh electrical wiring.

13 MAGNETIC EFFECTS OF ELECTRIC CURRENT CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions that follow on the basis of Uniform magnetic your understanding of the following source based field ‘B’ paragraph and the related studied concepts. Michael Faraday was an experimental physicist. He introduces the concept of the magnetic line (d) What is the direction of magnetic field lines of force to represent a magnetic field visually. outside a bar magnet? According to his experiment, when bar magnet is surrounded by little bits of iron filings, each a Ans. From North pole to South pole. little magnet of its own. By tapping the surface, the iron filings arrange themselves in a particular II. Answer the questions that follow on the basis of pattern. They respond to an unseen presence— your understanding of the following source based what Faraday called it “lines of force.” The paragraph and the related studied concepts: following sketch shows the lines of force due to a bar magnet on the accumulated action on little In the process of developing our modern iron filings. understanding of electricity, magnetism and electromagnetism, our predecessors carried out (a) What is magnet? various experiments and find that an electric Ans. A magnet is a piece of material that has both current in a wire has a heating effect, and may cause the wire to glow. This showed that the three attractive and directive properties. phenomena of electricity, heating and lighting (b) What happens if a bar magnet is cut into two were connected. Besides these they discover the concepts of charge, conservation of charge, the pieces along its length? nature of electric and magnetic fields. Ans. Two magnets are obtained and each having both Hans Christian Oersted, in 1820, was a Danish North and South pole. scientist noticed that a compass needle placed (c) Draw a diagram indicating uniform magnetic in close proximity deflected its initially aligned north-south direction in the presence of a field. current-carrying wire. That experiment has been Ans. Uniform magnetic field is represented by the the first one to indicate that current-carrying wire produces a magnetic field. He showed equidistance parallel lines as shown below: that electricity and magnetism were related phenomena. This experiment is one of the most important in the utilisation of electric power as it led to the discovery of electromagnetism and the development of the electric motor. His research later created technologies such as the radio, television and fibre optics. The unit of magnetic field strength is named the Oersted in his honour.

536 Together with® Science—10 (a) When lightning, a form of electricity, struck Sr. No. Table A Magnetic a ship, the ship’s compass might be affected Field – its polarity might be reversed. What does Current in this suggest? solenoid (A) (x 10-4 T) Ans. There is correlation between electricity and 1 0.5 2.51 magnetism. 2 1.0 3.14 3 1.5 3.77 (b) On what factors the strength and direction of 4 2.0 4.39 the magnetic field around a current carrying conductor depends on? Table B Ans. The strength and direction of the magnetic Sr. Length of No. of turns Magnetic field depends on the magnitude and direction of current. No. solenoid per metre Field (m–1) (x 10–4 T)) (c) Suppose a horseshoe magnet is held vertically (m) upwards with the North Pole is on left. A wire passing between the poles carries a direct 1 0.5 200 2.51 current directed away from you. In what direction is the magnetic force exert on the 2 1.0 250 3.14 wire? 3 1.5 300 3.77 Ans. According to Fleming’s Left Hand rule, the current carrying wire experiences a downward 4 2.0 350 4.39 magnetic force. (a) From the table, what relationship would (d) State the principle involved in the construction you observe between the (i) magnetic field of an electric motor. and current, and (ii) magnetic field and number of turns per metre of a solenoid? Ans. Principle : It works on the principle of magnetic effect of current. When a current Ans. (i) The magnetic field depends directly on the carrying conductor is placed perpendicular to current passing through it. the magnetic field, it experiences a force. (ii) The magnetic field depends directly on the III. Answer the questions that follow on the basis of number of turns per metre of a solenoid. your understanding of the following source based paragraph and the related studied concepts: (b) Why magnetic field inside the solenoid is uniform? A coil of many circular turns of insulated copper wire wound on a cylindrical insulating body (i.e. Ans. A solenoid is a long coil of wire wrapped in many cardboard etc.) such that its length is greater than turns. Each loop in the solenoid carries the same its diameter is called solenoid. When current is amount of current in the same direction when flowing through the solenoid, the magnetic field connected to the battery. The field produced is present inside the solenoid. These current due to each turn just adds up along the axis of carrying solenoids are used in electronic circuit a solenoid due to same direction and are in the and to form an electromagnet. By inserting form of parallel straight lines. This indicates that the magnetic field sensor between the coils of the magnetic field is uniform inside the solenoid. a solenoid, one can measure the magnetic field inside the solenoid and determine the relationship (c) How can magnetic field strength of a solenoid between the (i) magnetic field and current, and be increased? (ii) magnetic field and number of turns per metre in a solenoid. On performing the experiment Ans. The Magnetic field of a solenoid increases with the help of suitable apparatus, the following when we insert an iron core because iron itself observations were noted. magnetised due to strong uniform magnetic field produced by current carrying solenoid. This help in increasing the magnetic property of solenoid.

Case-based/Passage-based Integrated Questions 537 (d) For same current flowing through a solenoid (b) What is the main difference between An AC and a straight conductor, the magnetic field Generator and DC Generator? produced by a solenoid is much stronger than the magnetic field produced by a straight Ans. Sr. No AC Generator DC Generator current carrying conductor. State one reason to justify this statement. 1 In an AC In a DC Ans. Each segment of current produces a magnetic generator, the generator, the field like that of a long straight wire, and the total field due to all loops of a solenoid is the vector current changes current does sum of the fields due to each loop. Therefore, the magnetic field produced by a solenoid is much its direction not change its stronger than the magnetic field produced by a straight current carrying conductor. after equal direction with IV. Answer the questions that follow on the basis of intervals of time i.e current your understanding of the following source based paragraph and the related studied concepts: time. flows only in Electricity is the life-blood of modern society. It one direction. is supplied by the large power plants having ac generators through interconnected power grids. 2 AC generators DC generators The first electromagnetic generator was built in have slip-rings. have split-ring 1831 by British scientist Micheal Faraday based commutators. on the principle of electromagnetic induction discovered by him. Same principle is used by the (c) State the significance of split rings in an modern generators in today time. electric motor. In electricity generation, a generator is a device Ans. The split ring acts as a commutator in an electric that converts mechanical energy into electrical motor. With the help of split ring, the direction power as an output for the use in external of current through the coil is reversed after circuit. Generator is only an energy converter. every half rotation of coil and thus the direction Nothing can be generated by it whether it is an of currents (in both the arms) rotating the coil ac generator or dc generator. remains unchanged and the coil continues to rotate in the same direction. Sources of power generation range from conventional sources such as coal, lignite, natural (d) What is the difference between electromagnetic gas, oil, hydro and nuclear power to viable non- induction and electromagnetism? conventional sources such as wind, solar, and agricultural and domestic waste. The various Ans. In electromagnetism, on supplying the types of turbines used in electric generator are current, magnetic field is produced whereas steam turbines, water turbines, gas turbines and in electromagnetic induction, due to change in internal combustion engines. magnetic flux, induced current is produced in a closed circuit. (a) Name and state the rule that determine the direction of induced current in the coil. V. Answer the questions that follow on the basis of your understanding of the following source based Ans. Fleming’s Right Hand Rule: Stretch the thumb, paragraph and the related studied concepts. forefinger and middle finger of the right hand mutually perpendicular to each other such that In India, alternating current is supplied for the forefinger gives the direction of magnetic domestic purposes by power distribution field and the thumb points in the direction of the companies. Two separate wires live wire and motion of a conductor then, the middle finger neutral wire are used for this purpose. Live wire will give the direction of the induced current. is maintained at 220 V, while the neutral wire is at 0 V. As a result, a potential difference of 220 V is maintained across these two wires. A third wire called earth wire is also used in domestic circuits as a safety measure. We know that in domestic circuits, all the appliances are connected in parallel and are designed to handle a limited amount of electricity. In parallel circuits, if we add more and more appliances with too many branches, more current

538 Together with® Science—10 is drawn from the main supply. The circuit will (b) When current exceeds the fuse rating, fuse become overloaded; connecting wires heat up and gets blown off. Why? may cause fire. This is the great disadvantage of parallel circuits. Ans. Fuse element has high resistance and low melting point. It is connected in series with live wire. Dimming lights when you turn on other appliances, When current flows exceed the fuse rating, its warming of switch covers etc. are the indicators temperature increases. This make it overheated for overloading of circuits. The most important (H = I 2Rt). As a result, fuse element will melt indication for overloading is blown of fuse or and breaks the connection that was completing tripping of circuit breaker. This breaks the the entire circuit. continuous pathway of the circuit and circuit becomes inactive. The professional electrician (c) Mention the insulation colour of wires used diagnoses the problem and fixes it and than reset in domestic circuits. the circuit breaker or fuse. Ans. The insulation colour of wires used in domestic (a) What precautions should be taken to avoid circuit: overloading of domestic circuits? (i) Red colour insulation wire – Live wire Ans. The precautions that should be taken to avoid overloading of domestic circuits are (ii) Black colour insulation wire – Neutral wire (i) Too many appliances should not be (iii) Green colour insulation wire – Earth wire connected to a single socket at the same time. (d) Give one difference between the wires used in the element of an electric geyser and in a (ii) High power rating electrical device should fuse. not be used at the same time. Ans. High melting point material is used in electric geyser whereas fuse wire has a low melting point.

14 SOURCES OF ENERGY CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your (b) What steps would you suggest to minimise understanding of the following paragraph and the related studied concept. environmental pollution caused by burning of fossil fuels? In global energy systems, fossil fuels (coal, oil, gas) dominantly played a significant role. It is a Ans. To minimise environmental pollution caused fundamental driver of the Industrial Revolution, by the burning of fossil fuels we can do the and the technological, social, economic and following: development progress which has followed. (i) Use of appliances that are based on The rising economic activity and the increasing renewable source of energy. population are leading to rise in demand for energy in India. India’s current energy system (ii) Planting more trees i.e afforestation. is largely based on coal for power generation, oil for transport and industry. To fulfil the energy (c) Why is there so much emphasis on changing demand, India was the world’s sixth largest producer of coal, the 22nd largest producer of over from petrol/diesel driven automobiles to oil and 28th largest producer of gas in 2018. In CNG-driven vehicles? 2017, 61 per cent of domestic energy production and 75 per cent of total energy supply in India Ans. This is because came from fossil fuels. (i) CNG on burning produces only carbon The fossil fuels are non-renewable sources of dioxide and water but not produce smoke. energy and the supply of fossil fuels is finite, so we need to conserve them. If we were to continue (ii) It does not leave unburnt hydrocarbons, consuming these sources at such alarming rates, lead particulates, etc. which pollutes the we would soon run out of energy! In order to environment. avoid this, replacement of fossil fuel by renewable is not only important for the environmental (d) State the types of nuclear reactions that can sustainability or greenness of our development process, but also in the interest of the economic be used to create nuclear energy and elements sustainability of our growth process. used in them. (a) Which of the following power plants involves Ans. Nuclear energy can be obtained by two types of nuclear reactions: more running expenses and why? (i) Nuclear fission, and Thermal power station, hydro power station, an array of solar panel, wind energy farm or (ii) Nuclear fusion geothermal source. And elements used in them are Uranium-235 Ans. Thermal power stations involve more running and hydrogen respectively. cost due to continuous use of coal. II. Answer the questions on the basis of your understanding of the following paragraph and the related studied concept. India is the 7th largest country in the world spanning 328 million hectares and produces about 450-500 million tonnes of biomass per year. It is a renewable source of energy that contains complex mixture of carbon, nitrogen, hydrogen and oxygen. Biomass of this content is obtained

540 Together with® Science—10 from living or dead plants, by product of crop (ii) Making cow-dung cakes by drying it in the production, wood and agro based industry. sun and then burning it as a fuel. Biomass, plays a vital role especially in rural III. Answer the questions on the basis of your areas, provides 32% of all the primary energy understanding of the following paragraph and use in the country at present. So it constitutes the the related studied concepts. major energy source to majority of households in India. Sustainable development requires a continuous and efficient energy supply. Therefore, renewable Biogas technology provides an alternative source energy sources such as wind energy are vital for of energy mainly from biomass. The calorific value the Indian economy, not only from the point of of raw biogas having 55% methane concentration view of supply, but also from the perspective of is approximately 4713 kcal/m3 or 20 MJ. By using environmental and social benefits. The wind is the purification technology, the raw biogas can one of the unlimited sources of energy we have be purified up to 95% methane or even more. on earth. Now, we have built massive wind farms The purified biogas called Bio-Compressed to harness wind energy that would otherwise go Natural gas (Bio-CNG) can effectively be utilised unused. The largest windmill facilities in India are for cooking, industrial application and power installed in Muppandal in Kanyakumari district, generation through a biogas based power Tamil Nadu. It is one of the most important generation system. Organic Bio-manure is also sites of wind-farm in the state. It uses the wind produces as a by-product for organic farming that energy of wind coming from the Arabian Sea help in sustain the soil fertility and conserving to produce renewable energy. The suitability of water in irrigation. Muppandal as a site for wind farms stems from its geographical location as it has access to the (a) Why is burning firewood in traditional seasonal monsoon winds. chulhas considered disadvantageous? Power generation, to a larger extent, depends Ans. (i) The major amount of heat –produced on the installed capacity of the wind farm units. in burning of firewood is lost to the Wind farm units possessing a higher installation surroundings, only a very small percentage capacity are capable of producing power in large of heat is utilised for domestic purpose. quantities. For example, there are about 3000 turbines set up on the farm, which produces 1500 (ii) Lot of smoke is produced due to incomplete MW power of clean energy even when the wind combustion causing health problems and speed is fluctuating. pollution. In today scenario, India is the world’s fifth largest (b) List two fuels obtained from bio-mass. wind-power producer behind Germany, Spain, the United States and Denmark. Ans. The various fuels obtained from bio-mass are: (a) Why do you think Muppandal is at an (i) Biogas: obtained from animal waste (cow- advantageous position for this project? dung, etc.) Ans. The suitability of Muppandal as a site for wind (ii) Charcoal: obtained from wood. farms stems from its geographical location as it has access to the seasonal monsoon winds. (c) Why biogas is considered an ideal domestic fuel? Give any two reasons. Ans. Biogas is ideal domestic fuel because: (i) It does not producing any pollution - Smokeless flame, no ash. (ii) It is cheap fuel and has a high calorific value. (d) List two ways in which animal dung can be utilised as a fuel. Ans. The two ways in which animal dung can be utilised as a fuel are: (i) Anaerobic decomposition of animal dung produces bio-gas which can be used as fuel.

Case-based/Passage-based Integrated Questions 541 (b) Do windmills store energy? Our country is lucky to receive solar energy for the greater part of the year. It is estimated that Ans. Wind energy cannot be stored by windmills during a year India receives the energy equivalent itself although wind-generated electricity can to more than 5000 trillion kWh from the Sun. The be stored, if batteries are used. solar energy available in a single year exceeds the possible energy output of all of the fossil fuel (c) What is meant by wind energy farm? energy reserves in India. Ans. Number of windmills erected over a large area (a) What are solar cells? in a particular pattern is known as wind energy farm. Ans. A solar cell is a device that converts light (solar) energy into electrical energy. (d) From the power curve drawn for a wind turbine generator, determine the minimum (b) How much voltage can be developed and wind speed needed to turn the turbine in a how much electricity can be produced by one wind energy farm? typical solar cell when exposed to the Sun? 2,500 Ans. A voltage of about 0.5V to 1V is developed by the typical solar cell and can produce about 0.7 2,000 W of electricity when exposed to the Sun. Power Output [kw] 1,500 (c) Mention the purpose of blackening the interior of a solar cooker. 1,000 Ans. The purpose of blackening the interior of a solar 500 cooker is that the black surface absorbs more heat radiations of incident solar energy (about 10 98%) as compare to white or other light coloured 0 5 10 15 20 25 30 surface. Wind speed [m/s] (d) The future of power generation by solar Ans. The minimum wind speed to maintain the energy is bright in India. Give two reasons. required motion of the turbine in a wind energy farm is approximately 4.1 m/s. Ans. Solar energy is a renewable source of energy produced from sunlight. The future of power IV. Answer the questions on the basis of your generation by solar energy is bright in India understanding of the following paragraph and because: the related studied concept. (i) India is blessed with an infinite number of Solar power in India is a fast developing industry. natural resources and proximity to equator The country’s solar installed capacity reached helps brighten its vast pieces of lands with 30.071 GW as of 31 July 2019. India has the lowest sunlight. India receive the solar energy capital cost per MW to install solar power plants. equivalent to more than 5,000 trillion kWh Solar electricity generation recorded nearly 3.4% in an around 300 days of sunshine every of total utility electrical generation in January year. 2019. The following table shows annual solar power generation of the last seven years. (ii) Simplification norms of the government help to established large solar power plants Sr. Year Solar Power with greater production capacity in urban No. Generation(TWh) and rural areas with low running cost. 1 2013-14 3.35 2 2014-15 4.60 3 2015-16 7.45 4 2016-17 12.09 5 2017-18 25.87 6 2018-19 39.27 7 2019-20 49.45

15 OUR ENVIRONMENT CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your (a) What is biological magnification? understanding of the following paragraph and the related studied concept. Ans. Biological magnification refers to the process of increase in the concentration of toxic chemicals There are more than 1000 pesticides used with increasing trophic level in a food chain. around the world to ensure food is not damaged or destroyed by pests. Each pesticide has (b) Which chemical is banned from use by different properties and toxicological effects. the countries which sign 2001 Stockholm Many of the older, cheaper pesticides, such as Convention? dichlorodiphenyltrichloroethane (DDT) and lindane, can remain for years in soil and water. Ans. DDT These chemicals have been banned by countries who signed the 2001 Stockholm Convention – (c) Give one way by which human being can be an international treaty that aims to eliminate protected from intake of pesticide? or restrict the production and use of persistent organic pollutants. The toxicity of a pesticide Ans. People should wash and peel fruits and depends on its function and other factors. None vegetables before consumption. of the pesticides that are authorized for use on food in international trade today are genotoxic . (d) In an ecosystem, trophic level represents: Adverse effects from these pesticides occur only (i) Energy level above a certain safe level of exposure. When (ii) Water level people come into contact with large quantities (iii) CO2 level of pesticide, this may cause acute poisoning or (iv) Salt level long-term health effects, including cancer and Ans. (i) Energy level adverse effects on reproduction. II. Answer the questions on the basis of your Nobody should be exposed to unsafe amounts understanding of the following paragraph and of pesticide. People spreading pesticide on crops the related studied concept: should be adequately protected. People not directly involved in the spread of pesticides should Every living thing plays a role in the food chain stay away from the area during and just after and Earth’s ecosystems, and the extinction of a spread. Food that is sold should comply with certain species, whether predators or prey, can pesticide regulations, in particular with maximum leave behind significant impacts. Since the origin residue limits. Consumers can further limit their of life on Earth, it’s fair to say that more species intake of pesticide residues by peeling or washing have gone extinct than are currently alive now. fruit and vegetables, which also reduces other Extinction itself is part of the normal course of foodborne hazards, such as harmful bacteria. evolution. The effect of a species would have if it were to fade from existence depends largely on its role in the ecosystem. Predators, for example, are often the first to be threatened by hunting or competition with people and resources. When a

Case-based/Passage-based Integrated Questions 543 predator goes extinct, all of its prey are released Ans. Carnivores depend on the flesh of harbivores. from that predation pressure, and they may have Harbivores build up their tissues with the help big impacts on ecosystems. The loss of a predator of food for which they depend upon the plants. can result in what is called a trophic cascade, This justifies the statement that all the flesh of which is an ecological phenomenon triggered a carnivore is grass. by a predator’s extinction that can also impact populations of prey, which can cause dramatic (c) What will be the impact if all the organisms ecosystem and food web changes. If there are too of one trophic level die? Gives any one effect. many deer, for example, they can really change the ecosystem because they can destroy forests, Ans. If all the organisms of one trophic level die, then and they also carry disease. the organisms in the next trophic level will not get their food and hence they will either die or (a) What is an ecosystem? migrate to a different food chain. Ans. It is the structural and functional unit of (d) In an ecosystem, green plants represent: biosphere, comprising of all the interacting organisms in an area together with the non-living (i) Producers constituents of the environment. (ii) Primary consumers (b) Justify the statement; ‘All the flesh of a carnivore is grass’. (iii) Secondary consumers (iv) Decomposers Ans. (i) Producers

16 MANAGEMENT OF NATURAL RESOURCES CASE-BASED/PASSAGE-BASED INTEGRATED QUESTIONS I. Answer the questions on the basis of your outflow laws. In areas with high populations, understanding of the following paragraph and waterways used for drinking water are overdrawn the related studied concept. and are used for purposes such as the cleaning of clothes and bathing. Rainwater harvesting can Rainwater harvesting is a viable option to prevent the need to travel far distances to obtain supplement city water for non-potable human water and can help the overall health and growth uses, such as irrigation. The overall efficiency of communities. of a rainwater harvesting system to supplement (a) List one benefit of water harvesting. city water increases as area increases. The system Ans. It reduces storm water discharge, urban flood would be highly effective in high commercial regions where there are warehouses and large and overloading of sewage treatment plant. buildings. These areas also contain less lawn area, (b) Name one water harvesting system practiced so that the water can be used for uses beyond irrigation. In order to display the potential of in ancient India. the rainwater harvesting project for a heavy Ans. Khadins in Rajasthan commercial area, Ontario, CA was chosen as (c) What are the benefits of building a dam? a sample site. Ontario is an area with many Ans. Benefits of building a dam: commercial facilities, when all of the roof area (i) Generation of electricity is considered with the average annual rainfall at (ii) Irrigation 16 inches, a total of 2,200 acre-feet per year of (d) Which of the following is not a method for water can be collected, this can meet the demands of 10,000 people. water conservation? (i) Rainwater harvesting The simplicity of the model and the low overall cost (ii) Drip irrigation to install the system makes rainwater harvesting (iii) Groundwater extraction easily translatable for use in developing regions. (iv) None of these The water quality data shows that the water is Ans. (iii) Groundwater extraction clean for non-consumption purposes; although, a simple filtration system may have the ability II. Answer the questions on the basis of your to take the water into the potable range. The understanding of the following paragraph and water collected from the harvesting system is the related studied concept. actually cleaner than many water sources found in developing regions. In developing regions with We use plastics in virtually every shape and a growing industry sector, water sources are form in our daily lives. It carries our drinks, often contaminated by outflow of waste from the holds our shampoos, and keeps our veggies fresh. facilities as many countries do not have stringent According to the UN Environment Programme, humans are consuming resources and producing waste at a greater scale than ever before, and

Case-based/Passage-based Integrated Questions 545 per capita consumption levels are projected chemicals are known to cause cancer, and the to increase with continued development. Data manufacturing by-products contaminate our air indicates that during the 20th century, global and soil. material resource use rose at about twice the rate of population. Plastic is everywhere! We (a) What is sustainable development? love it because it is waterproof, relatively cheap, durable, and versatile. Plastic makes our lives Ans. Sustainable development is the development incredibly convenient, disposable, and easy, but which can be maintained for a long time without most people rarely think about the effects it has undue damage to the environment. on the environment. Unlike other materials, it never really goes away. Plastic does break down, (b) Why is plastic popular among human being? but in a landfill it takes up to four hundreds years; worse, it doesn’t ever become other materials, Ans. Plastic is popular because it is waterproof, it just breaks into microscopic pieces of plastic relatively cheap, durable and versatile. that are still non-biodegradable. From there, plastic fragments most often find their way into (c) How does high energy demand affect our the oceans. But it’s not just the end of a plastic’s environment? life cycle we need to worry about. When plastic is produced, it’s made from toxic materials Ans. To meet the increasing demand for energy, such as benzene and vinyl hydrochloride. These more and more natural resources are exploited. Pollutants are emitted during exploitation and use of natural resources which affect our environment. (d) How much time plastic needs to break down into microscopic pieces? Ans. 400 years