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Chemistry 10th

Published by Subhankar Das, 2023-07-07 15:02:01

Description: Chemistry 10th

Keywords: vedantutatva,class 10

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["METALS AND NON-METALS 51 \tQ.11.\t Explain why calcium metal after reacting with water starts floating on its surface. Write the chemical equation for the reaction. Name one more metal that starts floating after some time when immersed in water. \tQ.12.\t A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas oxide C causes global warming. Identify A, B and C. \tQ.13.\t An alkali metal A gives a compound B (molecular mass = 40 u) on reacting with water. The compound B gives a soluble compound C on treatment with aluminium oxide. Identify A, B and C and give the chemical equations for the reactions involved. \tQ.14.\t A solution of CuSO4 was kept in an iron pot. After a few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Write the equation of the reaction involved. \tQ.15.\t Give reasons for the following: \t(a)\tSodium metal is kept immersed in kerosene. \t(b)\tBlue colour of copper sulphate solution disappears when some aluminium powder is added to it. \tQ.16.\t Which of the following are not ionic compounds? \t(i)\tKCl\t (ii)\tHCl\t (iii)\tCCl4\t(iv)\tNaCl \t\tOptions: \t(a)\t(i) & (ii)\t(b)\t(ii) & (iii)\t(c)\t(iii) & (iv)\t(d)\t(i) & (iii) \tQ.17.\t Fill in the blank: During the formation of an ionic compound, the metal forms ________ and the non metal forms _________. \t\tOptions: \t(a)\tcation, cation\t (b)\tanion, cation\t (c)\tcation, anion\t (d)\tanion, anion \tQ.18.\t Which one of the given properties is not generally exhibited by ionic compounds? \t\tOptions: \t(a)\tSolubility in water \t(b)\tElectrical conductivity in solid state \t(c)\tHigh melting and boiling points \t(d)\tElectrical conductivity in molten state \tQ.19.\t Which of the following metals exists in its native state in nature? \t(i)\tCu\t (ii)\tAu\t (iii)\tZn\t (iv)\tAg \t \tOptions: \t(a)\t(i) & (ii)\t(b)\t(ii) & (iii)\t(c)\t(ii) & (iv)\t(d)\t(iii) & (iv) \tQ.20.\t The most abundant metal in the Earth\u2019s crust: \t\tOptions: \t(a)\tIron\t (b)\tAluminium\t (c)\tCalcium\t (d)\tSodium \tQ.21.\t The electronic configuration of three elements X, Y and Z are as follows: X = 2, 4; Y = 2, 7; and Z = 2, 1. Which two elements will combine to form an ionic compound and write the correct formula. Which of the following correctly represents the formula of an ionic compound formed by two of these three elements? \t\tOptions: \t(a)\tX2Y\t (b)\t ZY\t (c)\tXZ3\t(d)\t Y2Z \tQ.22.\t The atomic number of an element \u2018X\u2019 is 12. Which inert gas is nearest to X? \t\tOptions: \t(a)\tHe\t (b)\tAr\t (c)\tNe\t (d)\tKr","52 METALS AND NON-METALS \tQ.23.\t Why do ionic compounds have high melting points? \tQ.24.\t Name two metals which are found in nature in the free state. \tQ.25.\t Atomic numbers of Mg and O are 12 and 8 respectively. Show the process of formation of their compound by transfer of electrons. \tQ.26.\t Write electron dot diagram for chlorine (Z = 17) and calcium (Z = 20). Show the formation of calcium chloride by transfer of electrons. \tQ.27.\t Explain the formation of ionic compound CaO with the help of electron dot structure. \tQ.28.\t Write down important properties of ionic compounds. \tQ.29.\t Define the term \u2018metallurgy\u2019, and fill appropriate terms in the blanks: \t\tThe four major steps involved in metallurgy are: \t(i)\t______ of ore. \t(ii)\tConversion of ore into its _______ \t(iii)\tReduction of oxides of ores into ______ \t(iv)\t______ of impure metal. \tQ.30.\t (a)\tIn the formation of a compound between two atoms A and B, A loses two electrons and B gains one electron. \t\t (i) \tWhat is the nature of the bond between A and B? \t\t (ii)\tSuggest the formula of the compound formed between A and B. \t\t(b)\t Common salt conducts electricity only in the molten state. Why? \tQ.31.\t Which of the following is an application of thermite reaction? \t\tOptions: \t(a)\t Refining of metal\t\t\t (b)\tRailroad repair \t(c)\tMaking electrical wires\t\t\t (d)\tPrevent corrosion \tQ.32.\t An electrolytic cell consists of: \t(i)\tpositively charged cathode\t (ii)\tnegatively charged anode \t(iii)\tpositively charged anode\t\t\t (iv)\tnegatively charged cathode\t\t\t \t\tOptions: \t(a)\t(i) and (iv)\t(b)\t(iii) and (iv)\t(c)\t(i) and (iii)\t(d)\t(i) and (ii) \tQ.33.\t During electrolytic refining of zinc, it: \t\tOptions: \t(a)\tgets deposited on cathode\t\t (b)\tgets deposited on anode \t(c)\tgets deposited on cathode as well as anode\t (d)\tremains in the solution \tQ.34.\tThe process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called: \t\tOptions: \t(a)\tRoasting\t (b)\tReducing\t (c)\tCalcination\t (d)\tSmelting \tQ.35.\t Oxides of moderately reactive metals like Zinc, Iron, Nickel, Tin, Copper etc. are reduced by using: \t\tOptions: \t(a)\tAluminium as reducing agent\t (b)\tSodium as reducing agent \t(c)\tCarbon as reducing agent\t\t (d)\tCalcium as reducing agent","METALS AND NON-METALS 53 \tQ.36.\t In thermite welding, a mixture of _______ and _____ is ignited with a burning magnesium ribbon, which produces molten iron metal as a large amount of heat is evolved. \t\tOptions: \t(a)\tIron (III) oxide and aluminium powder\t (b)\tIron (II) oxide and aluminium powder \t(c)\tIron (III) chloride and aluminium powder\t (d)\tIron (III) sulphate and aluminium powder \tQ.37.\t Galvanisation is a method of protecting iron from rusting by coating with a thin layer of: \t\tOptions: \t(a)\tGallium\t (b)\tAluminium\t (c)\tZinc\t (d)\tSilver \tQ.38.\t (a)\t Define corrosion. \t\t(b)\tWhat is the corrosion of iron called? \t\t(c)\tHow will you recognize the corrosion of silver? \t\t(d)\tWhy is corrosion of iron considered a serious problem? \t\t(e)\tHow can we prevent corrosion of iron? \tQ.39.\t An ore on treatment with dilute hydrochloric acid produces brisk effervescence. What type of ore is this? What steps will be required to obtain metal from the enriched ore. \tQ.40.\t Suggest a method of reduction for the following metals during their metallurgical processes: \t(i)\tMetal \u2018A\u2019 which is one of the last 2nd or 3rd positions in the reactivity series. \t(ii)\tMetal \u2018B\u2019 which gives vigorous reaction even with water and air. \t(iii)\tMetal \u2018C\u2019 which is kept in the middle of the reactivity series. \tQ.41.\t During extraction of metals, electrolytic refining is used to obtain pure metals. \t(a)\t Which material will be used as anode and cathode for refining of silver metal by this process? \t(b)\tSuggest a suitable electrolyte also. \t(c)\tIn this electrolytic cell, where do we get pure silver after passing electric current? \tQ.42.\t What happens when \t(a)\tZnCO3 is heated in the absence of oxygen? \t(b)\tA mixture of Cu2O and Cu2S is heated? \tQ.43.\t Explain the steps for extraction of copper from its enriched sulphide ore. Write the reaction involved. \tQ.44.\t Pure iron is soft and stretches easily when hot. \t(a)\tHow does this property of iron change when: \t\t (i) \ta small amount of carbon is mixed with it? \t\t(ii) \tnickel and chromium are mixed with it? \t(b)\t Define an alloy. How is an alloy prepared? \t(c)\tAn alloy has low melting point and is therefore used for electrical fuse. Write its composition. \tQ.45.\t In Column I are given different methods of extraction. Match the methods used for the extraction of metals given in Column II: \t \t Column I\t Column II \t 1.\t Reduction with carbon\t \t 2.\t Electrolytic reduction\t Al, Zn, Na, Fe, Mn, Pb \t 3.\t Reduction with aluminium","54 METALS AND NON-METALS ASSERTIONS AND REASONING TYPE QUESTIONS (Self-Practice) \t I.\tDirections: In the following questions, two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: \t (a)\tBoth (A) and (R) are true and (R) is correct explanation of the assertion. \t (b)\tBoth (A) and (R) are true but (R) is not the correct explanation of the assertion. \t (c)\t(A) is true but (R) is false. \t (d)\t(A) is false but (R) is true. \t Q.1.\t Assertion (A): Metals are lustrous, malleable, ductile and are good conductors of heat and electricity. They are solids at room temperature, except mercury which is a liquid. \t\tReason (R): Metals can form positive ions by losing electrons to non-metals. \t Q.2.\t Assertion (A): Metals combine with oxygen to form basic oxides. Aluminium oxide and zinc oxide show the properties of both basic as well as acidic oxides. These oxides are known as amphoteric oxides. \t\tReason (R): Non-metals combine with oxygen to form acidic oxides (CO2, NO2, SO2) or neutral oxides (H2O, CO, N2O). \t Q.3.\t Assertion (A): A list of common metals arranged in order of their decreasing reactivity is known as an activity series. \t\tReason (R): Metals above hydrogen in the Activity series can displace hydrogen from dilute acids. \t\tA more reactive metal displaces a less reactive metal from its salt solution. \t Q.4.\t Assertion (A): The extraction of metals from their ores and then refining them for use is known as metallurgy. \t\tReason (R): An ore is the mineral from which metal can be obtained. \t Q.5.\t Assertion (A): The surface of some metals, such as iron, is corroded when they are exposed to moist air for a long period of time. This phenomenon is known as corrosion. \t\tReason (R): Corrosion of aluminium is advantageous as it forms a layer of oxide which protects the metal underneath from further corrosion. \t II.\tDirections: In the following questions, two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: \t (a)\tBoth (A) and (R) are true and (R) is correct explanation of the assertion. \t (b)\tBoth (A) and (R) are true but (R) is not the correct explanation of the assertion. \t (c)\t(A) is true but (R) is false. \t (d)\t(A) is false but (R) is true. \t Q.1.\t Assertion (A): Potassium and sodium are kept immersed in kerosene oil. \t\tReason (R): Potassium and sodium react so vigorously that they catch fire if kept in the open. \tQ.2.\tAssertion (A): Some metal oxides, such as aluminium oxide, zinc oxide show both acidic as well as basic behaviour. \t\tReason (R): Acidic or basic behaviour depends upon the temperature of the oxide. \t Q.3.\tAssertion (A): All metals react with oxygen at the same rate. \t\tReason (R): Silver and gold do not react with oxygen even at high temperature.","METALS AND NON-METALS 55 \t Q.4.\tAssertion (A): Different metals have different reactivities with water and dilute acids. \t\tReason (R): Reactivity of a metal depends on its position in the reactivity series. \t\tThe metals placed at the top of the series are most active. \t Q.5.\tAssertion (A): Iron does not burn on heating but iron filings burn vigorously when sprinkled in the flame of the burner. \t\tReason (R): At ordinary temperature, the surfaces of metals such as magnesium, aluminium, zinc, lead etc. are covered with a thin layer of oxide. The protective oxide layer prevents the metal from further oxidation. \t Q.6.\tAssertion (A): Ionic compounds have low melting and boiling points. \t\tReason (R): A considerable amount of energy is required to break the strong interionic attraction. \t Q.7.\tAssertion (A): Ionic compounds conduct electricity in molten state. \t\tReason (R): Movement of ions in the solid state is not possible due to their rigid structure. NOTES","56 METALS AND NON-METALS QUESTION BANK Short Answer Type Questions (3 Marks) \t Q.1.\t Why is sodium chloride soluble in water but not soluble in kerosene? \t Q.2.\t Give a reason to explain: \t(i)\t Why do aluminium sheets not corrode easily? \t(ii)\t Why is copper vessel covered with a green coating in rainy season? \t Q.3.\t A compound \u2018Z\u2019 is formed by the transfer of electrons from a metal \u2018X\u2019 to a non-metal \u2018Y\u2019. Identify the type of bond formed in the compound. List three general properties of the compounds formed by such type of bonds. \t Q.4.\t Out of the two metals P and Q, P is less reactive than Q. Suggest an activity to arrange these metals in the order of their decreasing reactivity. Support your answer with a suitable chemical equation. \t Q.5.\t Differentiate between roasting and calcination with examples. \t Q.6.\t Name the ore of mercury. How mercury is extracted from its ore? \t Q.7.\t Give reasons for the following: \t\t(i)\t Metals conduct electricity. \t\t(ii)\t\tNon-metals in general do not displace hydrogen from dilute acids. \t\t(iii)\t Aluminium easily combines with oxygen but still it can be used for making kitchen utensils. \t Q.8.\t State the conditions under which the following metals react with water. Write equation for each reaction. \t(a)\tNa\t (b)\tMg\t (c)\tFe \t Q.9.\t(a)\t A substance X, an oxide of a metal, is used extensively in the cement industry. This element is found in our bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the chemical reaction involved. \t\t(b)\t\tChoose a metal from the following metals which reacts only with hot water:\t \t\t\t Sodium, magnesium, iron. \t\t\t Mention the products formed during the reaction. \tQ.10.\t How metals can be differentiated from non-metals on the basis of any three chemical properties? \tQ.11.\t Write chemical equations for the reactions taking place when: \t\t(i)\t iron is strongly heated in air. \t\t(ii)\t lead carbonate is calcined. \t\t(iii)\t chromium oxide (Cr2O3) is heated with aluminium powder. \tQ.12.\t A, B and C are three elements which undergo chemical reactions according to the following equations: \tA2O3 + 2B \u2192 B2O3 + 2A \t3CSO4 + 2B \u2192 B2(SO4)3 + 3C \t 3CO + 2A \u2192 A2O3 + 3C \t(a)\t\tWhich element is the most reactive? \t(b)\tWhich element is the least reactive? \t(c)\tWhat is the type of reactions listed above? \tQ.13.\t Describe ionic compounds on the basis of the following properties: \t\t(i)\t Strong force of attraction between positive and negative ions. \t\t(ii)\t Solubility of compounds in water. \t\t(iii)\t Electrical conductivity.","METALS AND NON-METALS 57 \tQ.14.\t (a)\t \u2018Sodium is a highly reactive metal and it cannot be obtained from its oxide by heating with carbon\u2019. Give reason. \t\t(b)\t How can sodium be obtained from sodium chloride? \tQ.15.\t (i)\t Define the term \u2018anode mud\u2019. Name the electrode made of pure metal. \t\t(ii)\t Give the reactions taking place at cathode and at anode during the electrolytic refining of copper. \tQ.16.\t Name two metals which are purified by electrolytic refining. Mention the anode, cathode and the electrolyte used in the refining process. At which electrode would the pure metal be deposited? \tQ.17.\t (a)\t Consider the following chemical equation: \t\t\tFe2O3 + 2Al \u2192 Al2O3 + 2Fe \t\t\t Name two categories in which you can place this reaction. \t\t(b)\t Define the term \u2018Oxidation\u2019 of a substance and name the substance oxidised and the oxidising agent in the above reaction. \tQ.18.\tWhat is thermit reaction? How is it used to join the railway tracks or cracked machine parts? \tQ.19.\t(a) \tShow the formation of MgO by the transfer of electrons. \t\t(b) \tName the cation and anion. \t\t(c)\t Write three properties of ionic compounds. \tQ.20.\t Account for the following: \t\t(a) \tAluminium is more reactive than iron. But its corrosion is less than iron. \t\t(b) \tHydrogen gas is not evolved when zinc metal reacts with dil. HNO3. \t\t(c) \tCarbon is not used for reducing aluminium from aluminium oxide. \tQ.21.\t(a)\t Why calcium starts floating when added to water? \t\t(b)\t Most of the metals do not give hydrogen while reacting with nitric acid. Why? \t\t(c)\t Write equation for the reaction of iron with steam. Name the compound of iron obtained. \tQ.22.\t Define alloys . List the properties of alloys that makes them useful over pure metals. Explain this fact with suitable examples. \tQ.23.\t (a)\t Name two metals which react with dil. HNO3 to evolve H2 gas. \t \t(b)\t Why oxides of high reactive metals cannot be reduced by carbon? \t \t(c)\t What is formed when sodium absorbs moisture from air? Give equation also. \tQ.24.\t (a)\t Why the sulphide and carbonate ores are converted into oxides? \t\t(b)\t From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal: \t\t\t (i) \twhich reacts with water only on boiling, and \t\t\t (ii)\tanother which does not react even with steam. \tQ.25.\t (a)\t Name any one metal which reacts neither with cold water nor with hot water but reacts with heated steam to produce hydrogen gas. \t\t(b)\t Name two metals which have very low melting point. \tQ.26.\t (a)\t Name a non-metal which is lustrous and a metal which is non-lustrous. \t \t(b)\t Write balanced chemical equation for the reaction: Aluminium when heated in air. Write the name of the product. \t \t(c)\t Why do ionic compounds not conduct electricity in the solid state. Q.27.\t A solution of copper sulphate was kept in an iron pot. After few days the iron pot was found to have a number of holes in it. Explain the reason in terms of reactivity. Also write the chemical equation of the reaction involved. Q.28.\t What are ionic compounds? Why do ionic compounds not conduct electricity in the solid state?","58 METALS AND NON-METALS Long Answer Type Questions (5 Marks) \t Q.1.\t \t(a)\t Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores. \t\t\t(b)\t How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper. \t Q.2.\t \t(a)\t What type of ores are calcined? Illustrate giving a suitable example. \t\t\t(b)\t In what form the calcined ore is obtained and how it can be reduced? Give chemical equations of the reduction process involved for the example given by you. \t\t\t(c)\t Name two metals used as reducing agents by displacing metals of lower reactivity from their compounds. \t Q.3.\t (a) \t An ore on heating in air, gives sulphur dioxide gas. Name the method in each metallurgical step, that will be required to extract this metal from its ore. \t\t(b) \t State which of the following reactions will take place or not, giving suitable reason for each. \t\t\t\t Zn(s) + CuSO4(aq) \u2192 ZnSO4(aq) + Cu(s) \t\t\t\t Fe(s) + ZnSO4(aq) \u2192 FeSO4(aq) + Zn(s) \t Q.4.\t Here are some general statements. Give one exception for each statement. \t\t(i)\t Metals are lustrous. \t\t(ii)\t Metals are solids at room temperature. \t\t(iii)\t Metals have high melting points. \t\t(iv)\t Non-metals are non-Iustrous. \t\t(v)\t Non-metals are insulators or non-conductors of electricity. \t Q.5.\t What happens when: \t\t(i)\t\tA piece of calcium is dropped in water. \t\t(ii)\t Sodium is kept exposed in air. \t\t(iii)\t Iron nail is dipped in copper sulphate solution. \t\t(iv)\t Potassium is dropped in cold water. \t\t(v)\t Carbon dioxide is compressed in water at high pressure. \t\tGive chemical equation involved in all the above reactions and balance them. \t Q.6.\t Write chemical equation when zinc granules react with: \t(i)\tSulphuric acid\t (ii)\tHydrochloric acid\t (iii)\tAluminium chloride \t(iv)\tSodium hydroxide\t (v)\tNitric acid \t Q.7.\t Give reasons why: \t\t(i)\t Ionic compounds have high melting and boiling points. \t\t(ii)\t Ionic compounds are soluble in water. \t\t(iii)\t Ionic compounds are solid and somewhat hard. \t\t(iv)\t Ionic compounds conduct electricity in molten state. \t\t(v)\t The metals have tendency to lose electrons. \t Q.8.\t Give reason for the following: \t\t(i)\t Gold and platinum are used in jewellery. \t\t(ii)\t Copper cannot displace hydrogen from dilute acids. \t\t(iii)\t Stainless steel does not rust easily. \t\t(iv) \tMetals can be given different shapes according to our needs. \t\t(v) \tZinc does not give hydrogen gas on reacting with HNO3.","METALS AND NON-METALS 59 \t Q.9.\t \t(a)\t Carbon cannot be used as reducing agent to obtain Mg from MgO. Why? \t\t\t(b)\t How is sodium obtained from molten sodium chloride? Give equation of the reactions. \t\t\t(c)\t How is copper obtained from its sulphide ore? Give equations of the reactions.\t \tQ.10.\t \t(a)\tWrite the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air. \t\t\t(b)\t Explain what is galvanisation? What purpose is served by it? \t\t\t(c)\t Define an alloy. How are alloys prepared? How do the properties of iron change when: \t\t\t\t (i) s\t mall quantity of carbon, \t\t\t\t(ii) \tnickel and chromium are mixed with it. \tQ.11.\t \t (i)\t Explain the steps for extraction of copper from its sulphide ore. Write the balanced equations involved in the process. \t\t\t(ii)\t What is meant by refining of metals? Draw a diagram of electrolytic refining of copper and name the substances used as cathode, anode and the electrolyte. \tQ.12.\t\t(a)\t Name two metals which are obtained from their ores by simple heating. \t\t\t(b)\t Differentiate between calcination and roasting, taking examples of zinc ores. \t\t\t(c) \tWhat is thermit reaction? State its significance. NOTES","60 METALS AND NON-METALS APPLICATION BASED QUESTIONS (Self-Practice) \t Q.1.\tGive reasons for the following: \t\t(a)\t Generally metals are not found in their free state. \t\t(b)\t Metals are good conductors of heat. \t Q.2.\t An element A forms two oxides AO and AO2. The oxide AO is neutral whereas the oxide AO2 is acidic in nature. Would you call element A a metal or a non-metal? \t Q.3.\tExplain the following statements: \t\t(a)\t Most metal oxides are insoluble in water but some of these dissolve in water. What are these oxides and their solutions in water called?\t \t\t(b)\tAt ordinary temperature, the surfaces of metals such as magnesium, aluminium and zinc etc. are covered with a thin layer. What is the composition of this layer? State its importance. \t\t(c)\t Some alkali metals can be cut with a knife. \t Q.4.\tDistinguish between the following: \t\t(i)\t Electrolytic reduction and electrolytic refining \t\t(ii)\t Mineral and ore \t\t(iii)\t Alloys and amalgams \t Q.5.\tState three reasons for the following facts: \t\t(a)\t Sulphur is a non-metal. \t\t(b)\t Magnesium is a metal. \t\tOne of the reasons must be supported with a chemical equation. \t Q.6.\tGive reasons for the following: \t\t(a)\t We can store copper sulphate solution in a silver vessel but not silver nitrate solution in a copper vessel. \t\t(b)\t The reaction of zinc with dilute nitric acid does not produce hydrogen gas. \t\t(c)\t Food cans are coated with tin rather than zinc. NOTES","METALS AND NON-METALS 61 ANALYZING, EVALUATING & CREATING TYPE QUESTIONS (Self-Practice) \t Q.1.\tGive reason for the following: \t\t(i) \tMost metals conduct electricity well. \t\t(ii) \tThe reaction of iron (III) oxide, Fe2O3 with heated aluminium is used to join cracked machine parts. \t\t(iii) \tSodium, potassium and lithium are stored under oil. \t Q.2.\tState reasons for the following: \t \t\t(i) \tMetals are good conductors of heat. \t\t(ii) \tAddition of some silver to pure gold for making ornaments. \t\t(iii) \tInability of non-metals for displacing hydrogen from dilute sulphuric acid. NOTES","62 METALS AND NON-METALS CHAPTER TEST (Self-Practice) Time: 1\u00bd Hour\t Maximum Marks: 50 \tPAAnswer the following Questions: \t Q.1.\t Name one metal and one non-metal that exists in liquid state at room temperature.\t \t Q.2.\t Why metals can act as reducing agents while non-metal cannot? \t Q.3.\tWhat type of oxides are formed by: (a) Metals\t(b) Non-metals? \t Q.4.\tName two non-metals which are lustrous. \t Q.5.\t Name two metals: (a) which have very low melting points, (b) which are so soft that they can be cut with a knife. \t Q.6.\t Name two metals: (a) which are best conductors of heat, (b) which are comparatively poor conductors of heat. \t Q.7.\t What is meant by malleability? Name two most malleable metals. \t Q.8.\tWhat is meant by ductility? Name two most ductile metals. \t Q.9.\t Name two metal oxides which are: (a) water soluble (b) insoluble in water. \tQ.10.\t What is meant by anodising? Why is it done? \tQ.11.\t Write the electron-dot structure for Na and Cl atoms. How do these form a chemical bond? Name the type of bond so formed. Why does a compound so formed have high melting point? \tQ.12.\t Differentiate between metals and non-metals with respect to their chemical properties. \tQ.13.\t Differentiate between roasting and calcination. \tQ.14.\t Define the following terms: (a) Alloy (b) Corrosion. \tQ.15.\t What happens when: (a) iron reacts with steam? (b) calcium and potassium are put in water? \tQ.16.\t Show the formation of: (a) MgO (b) Na2O by the transfer of electrons. \tQ.17.\t Why do ionic compounds: (a) are hard and solids? (b) conduct electricity in their aqueous solution form or molten state? \tQ.18.\t How are the following metals reduced: (a) Metals which are highly reactive? (b) Metals which are in the middle of the reactivity series? \tQ.19.\t How you will obtain the following metals: (a) Mercury from cinnabar? (b) Copper from its ore copper glance? \tQ.20.\t What happens when: (a) manganese dioxide is heated with aluminium powder? (b) iron (III) oxide is heated with aluminium powder? \tQ.21.\t How will you extract metal M from its enriched sulphide ore, if M is in the middle of the reactivity series? Write various steps used in extracting this metal. \tQ.22.\t What is a reactivity series? Describe an activity to develop a reactivity series. \tQ.23.\t How electrolytic refining of copper is carried out? Explain in detail. \tQ.24.\t Define the following: (a) Amalgam (b) Ore (c) Mineral. \tQ.25.\t What is meant by corrosion? How corrosion is caused? How it can be prevented? What is the effect of corrosion on: (a) copper (b) silver? \tQ.26.\t (a) Make a flow chart to explain the various steps involved in the extraction of metals from ores. \t\t(b) Give four characteristics of ionic compounds. Or","METALS AND NON-METALS 63 \t\tGive reasons only: \t\t(a) \tNa, K and Li are stored under oil. \t\t(b) P\t t, Au and Ag are used to make jewellery. \t\t(c)\t Hydrogen gas is not evolved when metals react with nitric acid. \t\t(d) \tAluminium is a reactive metal, yet it is used to make utensils for cooking. \t\t(e)\t Aqueous copper sulphate solution should not be stored in an iron container. NOTES","ANSWER KEY","ANSWER KEY 65 CHAPTER 01 CHEMICAL REACTIONS AND EQUATIONS ASSERTIONS AND REASONING TYPE QUESTIONS (Self-Practice) \tI.\t 1.\t (b)\t 2.\t(a)\t 3.\t(a) \t\t4.\t(b)\t 5.\t(a) \tII.\t 1.\t (a)\t 2.\t(a)\t 3.\t(d) \t\t4.\t(a)\t 5.\t(b)\t 6.\t(a) QUESTION BANK Short Answer Type Questions (3 Marks) \t 1.\t (i)\t In manufacturing cement, quicklime is used and it is obtained by thermal decomposition of limestone. \t\t\tCaCO3(s) \uf8e7H\uf8e7eat\uf8e7\u2192 CaO(s) + CO2(g) \t\t(ii)\t In manufacturing photochromic glass, silver chloride\/bromide is used which turns grey in sunlight. \t\t\t\t2AgCl(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2(g) \t\t\t\t2AgBr(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Br2(g) \t2.\t (i)\tDecomposition reaction. \t\t(ii)\tOxidation. \t\t(iii)\tOxidation reaction. \t\t(iv)\tDisplacement reaction. \t3.\tIt is a displacement reaction. \t\t(i)\tMetal X is more reactive than metal Y. \t\t(ii)\tMetal X is displacing metal Y from its salt solution. A more reactive metal displaces less reactive one from its salt solution, X is more reactive than Y. \t4.\t (i)\tYellow. \t\t(ii)\tLead iodide (PbI2). \t\t(iii)\t 2KI \t + Pb(NO3)2 \u2192 PbI2\u2193 + 2KNO3 \t P\totassium Lead nitrate Lead Potassium iodide nitrate \t\t\t iodide\t \t\t(iv)\tThis is a double displacement reaction. It can also be called a precipitation reaction. \t5.\tAluminium being more reactive displaces ferrous ions from ferrous sulphate solution and this results in the appearance of holes in the aluminium can. \t\t 2Al (s) + 3FeSO4 (aq) \uf8e7\u2192 Al2 (SO4 )3 (aq) + 3Fe(s) (Ferrous sulphate) (Aluminium sulphate) \t6.\t (a)\tCombustion reaction is an oxidation reaction because it is always carried in the presence of air or oxygen. \t\t\tCH4(g) + 2O2(g) \u2192 CO2(g) + 2H2O(l) \t\t(b) \tBring a burning matchstick close to the mouth of the tube from which hydrogen gas escapes. The gas will immediately catch fire and this will be accompanied by pop sound.","66 ANSWER KEY \t7.\tFeSO4.7H2O is green in colour and loses water of crystallisation when it is heated. It is then decomposed to Fe2O3 (brown coloured), SO2 and SO3. \t\tFeSO4.7H2O \uf8e7A\uf8e7\uf026\uf026 \u2192 FeSO4 + 7H2O Green coloured \t\t2FeSO4(s) \uf8e7\u2192 Fe2O3(s) + SO2(g) + SO3(g) \t 8.\t (i)\tCaCO3 \uf8e7H\uf8e7eat\uf8e7\u2192 CaO(s) + CO2(g) \t\t(ii)\t2AgCl(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2(g) \t\t(iii)\t2H2O(l) \uf8e7E\uf8e7lect\uf8e7ricit\uf8e7y\u2192 2H2(g) + O2(g) \t 9.\t (a)\t When hydrated copper sulphate is heated, five molecules of water of crystallisation are removed and the blue colour of crystals turns white. \t\t\tIf we moisten the crystals again with water the blue colour reappears. \t\t\tCuSO4.5H2O(s) \uf8e7H\uf8e7eat\uf8e7\u2192 CuSO4 + 5H2O(g) \t \t\t Blue White \t \t(b)\t When gypsum is heated at 373 K plaster of paris is formed. \t\t\t CaSO4.2H2O \uf8e73\uf8e773K\uf8e7\u2192 CaSO4. 1 H2O + 1 1 H2O 2 2 \t (c)\t Bleaching powder is formed \t\t\t Ca(OH)2 + Cl2 \uf8e7\u2192 CaOCI2 + H2O \t Dry slaked Chlorine Bleaching lime powder \t10.\t (i)\t Change in colour : ttReaction between lead nitrate solution and potassium iodide solution. Change in colour from colourless to yellow. \t\t\tPb(NO3)2(aq) + 2KI(aq) \u2192 PbI2(s) + 2KNO3(aq) \t\t\t\t\t Yellow precipitate \t\t(ii)\tChange in temperature : Action of dil. sulphuric acid on zinc. \t\t\tZn(s) + H2SO4(aq) \u2192 ZnSO4(aq) + H2 \t\t(iii)\tFormation of precipitate : Action of barium chloride on sodium sulphate. \t\t\tBaCl2(aq) + Na2SO4(aq) \u2192 BaSO4(s) + 2NaCl(aq) \t11.\t (a)\t (i)\tElectricity : \t\t\t\t\t2H2O(g) \uf8e7Ec\uf8e7ulercrte\uf8e7rnict\u2192 2H2(g) + O2(g) \t\t\t(ii)\tHeat : \t\t\t\t\tCaCO3(s) \uf8e7H\uf8e7eat\uf8e7\u2192 CaO(s) + CO2 \t\t\t(iii)\tSunlight : \t\t\t\t2AgCl(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2(g) \t \t (b)\tCopper can displace silver from silver nitrate solution because it is more reactive than silver. \t\tCu(s) + 2AgNO3(aq) \u2192 Cu(NO3)2(aq) + 2Ag(s) \t12.\t (i)\t(a)\tAt anode, oxygen gas is evolved. \t\t\t(b)\tAt cathode, hydrogen gas is evolved. \t \t (ii)\tThe amounts of gases collected in the two test tubes are of not the same volume because in water, hydrogen and oxygen are present in the ratio of 2 : 1 by mass.","ANSWER KEY 67 \t\t(iii)\tThis reaction is decomposition reaction. \t\t(iv)\tTo conduct electricity through it. \t 13.\t (a)\t2H2(g) + O2 (g) \u2192 2H2O (l) + Heat \t\t(b)\tOxidising agent-Cl2, \t\t\tReducing agent-H2S \t\t(c)\tRancidity, keeping food in airtight containers. \t 14.\t (i)\tMetal is copper. \t\t\t\tBlack coloured substance is copper oxide. \t\t(ii)\t2Cu + O2 \uf8e7\u2206\uf8e7\u2192 2CuO \t\t\tCuO + H2 \uf8e7\u2206\uf8e7\u2192 Cu + H2O \t 15.\t (a)\t It is a photochemical decomposition reaction. It can be defined as the decomposition of a substance in presence of sunlight in which a single reactant breaks down to give simpler products. \t\t(b)\tWhite silver chloride changes to grey, as it decomposes to silver and chlorine in the presence of sunlight. \t\t\t2AgCl(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2(g) \t\t(c)\tBlack and white photography. \t 16.\t (a)\t\tIt is a combination reaction. It is defined as a reaction in which a single product is formed from two or more reactants. \t\t(b)\tCaO(s) + H2O(l) \u2192 Ca(OH)2(aq) \t\t\t\t Calcium hydroxide \t\t(c)\tCalcium oxide : \t\t\t (i) r\teacts vigorously with water. \t\t\t(ii)\treleasing a large amount of heat. \t 17.\t (i)\tX - Copper (Cu), Process - Corrosion \t\t(ii)\tGreen coating is - Basic copper carbonate \/ Copper carbonate CuCO3.Cu(OH)2. \t\t(iii)\tPainting, oiling, greasing, galvanising, chrome plating, anodising or alloying. \t 18.\t (i)\tBefore heating - Pale green. After heating - Brown or reddish brown. \t\t(ii)\tSO2 and SO3. \t\t(iii)\t2FeSO4(s) \uf8e7H\uf8e7eat\uf8e7\u2192 Fe2O3(s) + SO2(g) + SO3 (g) \t19.\t (a)\t \u2022\tMnO2 is an oxidant\/ oxidizing agent; as MnO2 undergoes reduction. \t\t\t\u2022\t\tHCl is a reductant\/ reducing agent. HCl is getting oxidized. \t\t(b)\t(i) \tTo prevent rancidity of fats and oils. \t\t\t(ii) \tSilver chloride undergoes decomposition when exposed to sunlight to form silver and chlorine. Silver is grey in colour. \t\t\t\t2AgCl \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag (s) + Cl2 grey \t20.\tWater of crystallization is the fixed number of water molecules present in one formula unit of a salt. \t\t Hydrated copper sulphate \u2013 CuSO4.5H2O \/ Gypsum CaSO4. 2H2O","68 ANSWER KEY \t21.\t (a)\t (i) \tSilver articles react with sulphur present in the form of gases in air. Phenomenon is Corrosion. \t\t\t(ii) \tSilver Sulphide \t\t\t\t Ag2S \t\t(b)\t(i) \tCa3(PO4)2 (ii) (NH4)2CO3 \t 22.\t (i)\t In the electrolysis of water, the gas collected at cathode is hydrogen and the gas collected at anode is oxygen. \t\t(ii) \tThe gas which is collected in double the amount during the electrolysis of water is hydrogen. This is because water contains two parts of hydrogen element as compared to one part of oxygen element by volume. \t\t(iii)\tPure water is a bad conductor of electricity which does not undergo electrolysis. On adding drops of sulphuric acid it becomes a good conductor of electricity due to which electrolysis takes place. \t 23.\t (i)\t The white silver chloride turns grey in sunlight. This is due to the decomposition of silver chloride into silver and chlorine by light. \t\t(ii)\t2AgCl(s) \uf8e7S\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2(g) \t\t(iii)\tPhotochemical decomposition reaction. Or \t \t (a)\tZn (s) + 2 AgNO3(aq) \uf8e7\u2192 Zn(NO3)2 (aq) + 2Ag(s) \t\t\tReaction : Displacement reaction \t\t(b)\t2KI(aq) + Pb(NO3)2(aq) \uf8e7\u2192 2KNO3 (aq) + PbI2(s) \u2193 \t\t\t yellow precipitate \t\t\tReaction : Double displacement reaction Long Answer Type Questions (5 Marks) \t1.\t (a)\t 6CO2(aq) + 12H2O(l) \uf8e7C\uf8e7hSluo\uf8e7nrolipghh\uf8e7yt ll\uf8e7\u2192 C6H12O6(aq) + 6O2(aq) + 6H2O(l) \t\t\t\t\t Glucose \t\t(b)\t(i)\tEndothermic reaction \t \t \t(ii)\tExothermic reaction \t \t \t(iii)\tEndothermic reaction \t \t \t(iv)\tExothermic reaction \t2.\t (a)\t Corrosion : The process in which metals breakdown gradually by the action of air, moisture or a chemical on their surface. \t \t (b)\tRusting of iron. \t \t (c)\tBy the development of a black coating on silver. \t \t (d)\tEvery year enormous amount of money is spent to replace damaged iron. \t \t (e)\tPaint, galvanisation, electroplating. (any one) \t3.\t (a)\t3Fe(s) + 4H2O(g) \u2192 Fe3O4(s) + 4H2(g). \t \t (b)\tDouble displacement reaction. \t \t (c)\t(i)\tBlack coloured substance is copper oxide. It is formed because oxygen is added to copper. \t\t\t(ii)\tCopper (II) oxide (CuO). \t\t\t(iii)\t2Cu + O2 \uf8e7H\uf8e7eat\uf8e7\u2192 2CuO.","ANSWER KEY 69 \t4.\t (a)\t 3H2(g) + N2(g) \uf083 2NH3(g) \t \t (b)\t2H2S(g) + 3O2(g) \uf8e7\u2192 2SO2(g) + 2H2O(g) \t\t(c)\t3BaCl2(aq) + Al2(SO4)3(aq) \uf8e7\u2192 2AlCl3(aq) + 3BaSO4(s) \t\t(d)\t2K(s) + 2H2O(l) \uf8e7\u2192 2KOH(aq) +H2(g) \t\t(e)\tAlCl3(aq) + 3NH4OH(aq) \uf8e7\u2192 A\t l(OH)3(s) \u2193 + 3NH4Cl(aq) APPLICATION BASED QUESTIONS (Self-Practice) \t1.\tP4(s) + 10 Cl2(g) \uf8e7\uf8e7\u2192 4PCl5(g) \t 2.\t (i)\tDazzling white light can be seen during burning of magnesium. \t\t(ii)\tWhite powder is obtained after burning of magnesium in air. \t 3.\t (i)\tDisplacement reaction \t\t(ii)\tCombination reaction \t\t(iii)\tDecomposition reaction \t\t(iv)\tDouble displacement reaction \t 4.\t (i)\t3MnO2 + 4Al \uf8e7\u2192 2Al2O3 + 3Mn \t\t(ii)\t3Fe(s) + 4H2O(g) \uf8e7\u2192 Fe3O4(s) + 4H2(g) \t5.\tA chemical equation is a shorthand representation of a chemical reaction using the symbols and formulae of substances involved in the chemical reaction. \t\t An unbalanced chemical equation is only a skeletal chemical equation which gives the information about reactants and products and not about their actual number involved. \t 6.\t (i)\t\t2KClO3 \uf8e7\u2192 2KCl + 3O2 \t\t(ii)\tNa2CO3 + 2HCl \uf8e7\u2192 2NaCl + H2O + CO2 \t 7.\t (i)\tCaCO3 + 2HCl \uf8e7\u2192 CaCl2 + H2O + CO2 \t \t (ii)\tN2 + 3H2 \uf8e71\uf8e7atm\uf8e7.\u2192 2NH3 \t \t (iii)\tCS2 + 3O2 \uf8e7\u2192 CO2 + 2SO2 \t 8.\t (a)\tZn(s) + dil. H2SO4(aq) \uf8e7\u2192 ZnSO4(aq) + H2\u2191 \t\t (i)\t The container of the reaction mixture becomes hot as it is an exothermic reaction. \t\t (ii)\t Bubbles are seen with the evolution of H2 gas, which is combustible gas. \t \t (b)\t2KI(aq) + Pb(NO3)2(aq) \uf8e7\u2192 PbI2(s) \u2193 + 2KNO3(aq) \t\t\t\t\t Yellow \t\t (i)\t Yellow colour of potassium iodide solution disappears. \t\t (ii)\t Yellow precipitate of lead iodide is formed. \t \t (c)\t2Pb(NO3)2 \uf8e7S\uf8e7tron\uf8e7gly\uf8e7hea\uf8e7ted\u2192 2PbO(s)+4NO2(g)+ O2(g) \t\t (i)\t Yellow fumes of NO2 gas are observed \t\t (ii)\t White powder residue is obtained. \t9.\tApplications of a decomposition reaction : \t \t (a)\tWhite silver chloride turns grey in sunlight due to the decomposition of silver chloride into silver and chlorine.","70 ANSWER KEY \t\t\t2AgCl(s) \uf8e7s\uf8e7unl\uf8e7ight\uf8e7\u2192 2Ag(s) + Cl2. \t\t\t\tIt is used in black and white photography. \t\t(b)\tKCIO3 decomposes on heating and oxygen gas is prepared. \t\t\t2KCIO3 \uf8e7H\uf8e7eat\uf8e7\u2192 2KCl + 3O2\u2191 \t \t (c)\tQuicklime can be prepared by thermal decomposition of calcium carbonate (limestone). \t\t\tCaCO3(s) \uf8e7H\uf8e7eat\uf8e7\u2192 CaO(s) + CO2\u2191 \t\t\tCaO is used to prepare slaked lime which is used in whitewashing. \t10.\tObservations : \t\t(a)\tReaction takes place vigorously. \t\t(b)\tA large amount of heat is produced. \t\tUses of the product Ca(OH)2 : (a) It is used for whitewashing walls. It slowly reacts with the CO2 in air to form a thin layer of calcium carbonate on the walls. \t\t(b) It is used as a laboratory reagent for testing the presence of CO2 gas. \t11.\t (i) \tThe metal has been corroded. \t\t(ii) \tMetal is copper. \t\t(iii) \tGreen coating is basic copper carbonate CuCO3.Cu(OH)2. \t\t(iv) \tProtect from moisted CO2 air. \t\t(v) \tMaking alloys of copper. \t12.\t (i)\tAl lies above the Hydrogen, hence it displaces Hydrogen from dil. HCl solution and H2 gas is evolved. \t\t\t2Al(s) + 6HCl(aq) \uf8e7\u2192 2AlCl3(aq) + 3H2(g) \t\t(ii)\tZinc displaces Cu from its solution \t\t\tZn(s) + CuSO4 (aq) \uf8e7\u2192 ZnSO4 (aq) + Cu(s) Blue colour Colourless \t\t(iii)\t Silver metal being less reactive than copper cannot displace copper from its salt solution, therefore, no reaction occurs. \t13.\t (i)\tCaCO3 + 2HCl \uf8e7\u2192 CaCl2 + H2O + CO2 \t \t (ii)\t2Al + 6HCl \uf8e7\u2192 2AlCl3 + 3H2 \t \t (iii)\tMnO2 + 4HCl \uf8e7\u2192 MnCl2 + Cl2 + 2H2O \t14.\t (i)\t Combination reaction : Two or more substances combine to form single substance. \t\t(ii)\t Displacement reaction : One element takes the place of another element in a compound. \t\t(iii)\t Displacement reaction : More reactive metal displaces less reactive metal from its salt solution. \t\t(iv)\t Decomposition reaction : A compound splits up into two or more simpler substances. \t\t(v)\t Double displacement reaction : In which two compounds react by an exchange of ions to form two new compounds. ANALYZING, EVALUATING & CREATING TYPE QUESTIONS (Self-Practice) \t 1.\t (i)\t It does not allow air (oxygen) to come in contact with the food and this prevents oxidation of food. Thus, the food never becomes rancid and its smell and taste remain the same.","ANSWER KEY 71 \t\t(ii)\tMoist air causes corrosion of iron while acidic gases causes corrosion of copper and silver. \t\t(iii)\tNitrogen being inert prevents oxidation of food. \t 2.\t (i)\t Sodium reduces chlorine atom to chloride ion, therefore, it acts as reducing agent while chlorine oxidises sodium atom to sodium ion, therefore, it acts as oxidising agent. \t \t(ii)\tThis is due to the decomposition of silver chloride into silver and chlorine by light. \t\t(iii)\t In a decomposition reaction, one substance [compound] splits to give two or more simpler substances [elements or compounds] whereas in a combination reaction, two or more substances [elements or compounds] combine to form a single substance. Due to this reason, a decomposition reaction is called opposite of combination reaction.","72 ANSWER KEY CHAPTER 02 ACIDS, BASES AND SALTS ASSERTIONS AND REASONING TYPE QUESTIONS (Self-Practice) \tI.\t 1.\t (b)\t 2.\t(b)\t 3.\t(b) \t\t4.\t(b)\t 5.\t(b) \tII.\t 1.\t (b)\t 2.\t(a)\t 3.\t(b) \t\t4.\t(b)\t 5.\t(b)\t 6.\t(b) QUESTION BANK Short Answer Type Questions (3 Marks) \t1.\tCalcium phosphate ; below 5.5 ; bacteria produce acids by degradation of sugar and food particles remaining in the mouth after eating ; using tooth pastes which are generally basic. \t 2.\t (i)\t T\the pH range of a base is 7-14. \t\t(ii)\tThe strength of bases depends on the number of OH\u2013 ions produced. So by adding OH\u2013 ions, the strength of basic solution can be increased. \t\t(iii)\t\u2022 \tStrong base : Sodium hydroxide solution. \t\t\t\u2022 W\teak base : Magnesium hydroxide (Milk of magnesia). \t3.\tAcids ionise in aqueous medium to form hydrogen ions. These hydrogen ions cannot exist alone, they exist after combining with water molecules. Thus, aqueous hydrogen ions which are responsible for acidic behaviour can exist in the presence of water only. \t\tH+ ion + H2O \uf8e7\u2192 H3O+ Hydrogen Water Hydronium ion \t\tThese hydrogen ions are shown as H+(aq) or hydronium ions (H3O+). \t 4.\t (a)\t\tLime water turns milky due to the formation of insoluble white precipitates of calcium carbonate. \t\t\t\tCa(OH)2 (aq) + CO2 (g) \uf8e7\u2192 CaCO3 (s) \u2193 + H2O (l) Lime water [In limit] [White precipitate] \t\t(b)\t The white precipitate of CaCO3 gets dissolved in excess of CO2 to form calcium hydrogen carbonate which is soluble in water. \t\t\tCa(OH)2 (aq) + 2CO2 (g) \uf8e7\u2192 Ca(HCO3 )2 (aq) Lime water [In excess] Calcium hydrogen carbonate (Soluble in water ) \t 5.\t (a)\t(i) Blue (ii) White. \t\t(b)\tCrystals of copper sulphate (CuSO4.5H2O) contain water of crystallisation and on heating, these crystals loose water and become white. This lost water can be seen in the form of droplets on the inner upper side of the test tube. \t6.\tBleaching powder is prepared by the action of chlorine (Cl2) on dry slaked lime [Ca(OH)2]. \t\tCa(OH)2 + Cl2 \uf8e7\u2192 CaOCl2 + H2O \t Calcium Chlorine Calcium Water hydroxide (dry) gas oxychloride","ANSWER KEY 73 \t \t (i)\tIt smells strongly of chlorine because CO2 present in air reacts with it liberating free chlorine. \t\t(ii)\tIt contains some unreacted lime which is insoluble in water. Due to this reason, some milkiness persists when bleaching powder is dissolved in water. \t7.\tNa2CO3.10H2O \u2013 Hydrated salt \/ Sodium carbonate with water of crystallisation (Sodium carbonate decahydrate). \t\tNa2CO3 \u2013 Anhydrous salt \/ Sodium carbonate \t\t10H2O means water of crystallisation. It imparts colour and shape to the crystals. \t 8.\t (i)\t2NaOH(aq) + Zn(s) \uf8e7\u2192 Na2ZnO2(aq) + H2(g) \t\t(ii)\tTest : Hydrogen gas burns with a pop sound. \t\t(iii)\tZn(s) + H2SO4(aq) \uf8e7\u2192 ZnSO4(aq) + H2(g) \t\t\tGas evolved is hydrogen. \t 9.\t (i)\tSalt is NaHCO3 (Sodium hydrogen carbonate) \t\t(ii)\tPreparation of NaHCO3. By passing carbon dioxide through ammoniacal brine. \t\t\tCO2 + NH3 + NaCl + H2O \uf8e7\u2192 NH4Cl + NaHCO3 \t Ammoniacal Brine \t\t(iii)\tUses of NaHCO3 : \t\t\t(a)\t As an ingredient in antacids. Being alkaline, it neutralises excess acid in the stomach and provides relief. \t\t\t(b)\t It is also used in soda-acid fire extinguishers. \t\t\t(c)\t For making baking powder which causes bread or cake to rise making them soft and spongy. \t10.\tX - Sodium hydrogen carbonate (NaHCO3) \t\t Y - Carbon dioxide (CO2) \t\t Z - Sodium carbonate (Na2CO3). \t\t2NaHCO3 \uf8e7H\uf8e7eat\uf8e7\u2192 Na2HCO3 + H2O + CO2 Baking soda Sodium carbonate Water Carbon dioxide \t 11.\t (i)\tX is lime water Ca(OH2). \t\t(ii)\tDue to the formation of calcium carbonate, lime water turns milky when carbon dioxide gas is passed through it. \t\t(iii)\tCa(OH)2 + CO2 \u2192 CaCO3 + H2O \t 12.\t (i)\tThe purpose of developing pH scale was to quantify the amount of H+ or OH\u2013 ions in a solution. \t\t(ii)\tThe pH range for acids is 0\u20147. \t\t(iii)\t When pH of rain water is less than 5.6, it is called acid rain. It lowers the pH of river water. Thus, the survival of aquatic life becomes difficult. \t 13.\t (a)\t(i)\t Out of the hydrochloric acid and acetic acid of same concentration, acetic acid will produces less H+ ions. \t\t\t(ii)\t Acetic acid. \t\t(b)\tIf someone is suffering from acidity, I would suggest baking soda solution to cure it because it neutralises the excess acid produced in the stomach and provides relief. \t 14.\t (a)\t\tCa(OH)2 + Cl2 \uf8e7\u2192 CaOCl2 + H2O Bleaching powder \t\t(b)\tCaSO4. \u00bd H2O + 1\u00bd H2O \uf8e7\u2192 CaSO 4 .2H2 O Gypsum","74 ANSWER KEY \t \t (c)\tNaCO3. 10H2O \uf8e7a\uf8e7ir\u2192 Na2CO3.H2O +\u20099H2O Sodium carbonate monohydrate \t 15.\t (a)\t(i)\t formic acid\/methanoic acid \t\t\t(ii)\t citric acid \t (iii)\t lactic acid \t\t\t(iv)\t oxalic acid \t\t(b)\t(i)\t Sodium carbonate (Na2CO3) \t \t \t(ii)\t Sodium sulphate (Na2SO4) \t 16.\t (a)\tIt loses its 5 molecules of water of crystallisation hence colour changes. \t\t(b)\tIt is alkaline and neutralises excess acid to relieve pain. \t\t(c)\tAs dilution of acids is an exothermic reaction and adding water to acids will splash and cause burns. \t 17.\t (a)\tCa(OH)2 + Cl2 \u2192 CaOCl2 + H2O \t\t(b)\tNaHCO3 + Dil. HCl \u2192 NaCl + CO2 + H2O \t\t(c)\t2NaHCO3 \uf8e7\u2206\uf8e7\u2192 Na2CO3 + H2O + CO2 \t 18.\t (a)\t(i)\t Solution \u2018A\u2019 with pH = 0 has highest concentration of H+ ions. \t\t\t(ii)\t Solution \u2018C\u2019 with pH = 5 has the lowest concentration of H+ ions. \t \t (b)\t HCl solution is a strong acid and, therefore, ionises completely as compared to CH3COOH solution which is a weak acid. Due to complete ionisation, it contains high concentration of H+ ions. \t 19.\t (a)\t When burning candle is brought near to the jar filled with hydrogen gas, it burns explosively with a pop sound. \t\t(b)\t Since hydrogen ions cannot exist alone, therefore, they exist after combining with water molecules. Thus, hydrogen ions must be shown as H+(aq) or hydronium ion(H3O+). \t \t (c)\tOn dilution, the concentration of hydrogen ions per unit volume decreases and hence pH of the solution increases. Since pH is the negative logarithmic value of the concentration of hydrogen ions. \t 20.\t(a)\t \u00b7 MCO3 + 2HCl \uf8e7\u2192 MCl2 + H2O + CO2 \u2191 (X) Brisk Effervescene \t\t\t\u00b7 Ca(OH)2 + CO2 \uf8e7\u2192 CaCO3 \u2193 + H2O White ppt. \t\t(b)\t Chemical name : Calcium oxychloride \t\t\tChemical formula : CaOCl2 \t 21.\t (a)\t pH scale measures the hydrogen ion concentration in a solution thus indicating acidic\/basic nature of a solution. \t\t(b)\tFrom 0 to 14 \t\t(c)\t Significance : Highest value - very basic \/ alkaline solution. Lowest Value \u2014 Very acidic solution. \t22.\tThe name of the compound is Plaster of Paris \t\t Its chemical formula is CaSO4.\u00bdH2O \t\t Equation : CaSO4.2H2O \u2192 CaSO4.\u00bdH2O + 1\u00bd H2O \t\t It is used in the hospitals mainly as plaster for supporting fractured bones in the right position.","ANSWER KEY 75 \t 23.\t (i)\tB is NaOH. \t\t\tIt is a neutralisation reaction. \t\t(ii)\t2NaOH + SO2 \uf8e7\u2192 Na2SO3 + H2O \t 24.\t (a)\tNa2CO3 . 10H2O \t\t(b)\t2 NaHCO3 \uf8e7\u2206\uf8e7\u2192 Na2CO3 + H2O + CO2 \t\t\tNa2CO3 + 10H2O \uf8e7R\uf8e7ecr\uf8e7ysta\uf8e7llisa\uf8e7tion\uf8e7\u2192 Na2CO3.10H2O process \t\t(c)\t(i)\t Washing soda is used in glass, soap and paper industries. \t\t\t(ii)\t It is used in the manufacture of sodium compounds such as borax. \t 25.\t (i)\tHCl (strong acid) and NaOH(strong base). \t\t(ii)\tNeutral salts (Because it is formed by the complete neutralisation process). \t\t(iii)\t It is called rock salt when it gets deposited in the form of large crystals. It is brown due to impurities. \t\t(iv)\tBeds of rock salts were formed when seas of bygone ages dried up. Long Answer Type Questions (5 Marks) \t 1.\t (a)\tHydrated copper sulphate CuSO4.5H2O \t\t\tAnhydrous copper sulphate CuSO4 \t\t\tFor activity refer question in ABQ \t\t(b)\tCalcium sulphate hemihydrate CaSO4. 1 H2O 2 \t\t\tCalcium sulphate dihydrate CaSO4.2H2O \t2.\t (i)\t CaOCl2 (s) + CO2 (s) \u2192 CaCO3 (s) + Cl2 (s) Bleaching powder Carbon dioxide Calcium carbonate Chlorine \t\t(ii)\t CuSO4.5H2O \uf8e7H\uf8e7eat\uf8e7\u2192 CuSO4 + 5H2O Blue White \t\t(iii)\t Ca(OH) + Cl 2 \u2192 CaOCl2 + H2O Dry slaked lime Chlorine Bleaching powder \t\t(iv)\t Ca(OH)2 + CO2 \u2192 CaCO3 + H2O Lime water Calcium carbonate (Milky ppts.) \t\t(v)\t2NaOH + Zn \uf8e7H\uf8e7eat\uf8e7\u2192 Na2ZnO2 + H2 Sodium zincate Hydrogen \t 3.\t (a)\t Vigorous reaction will be seen in test tube A. \t\t(b)\tIt is because H2SO4 is stronger acid than H2CO3. \t\t(c)\t (i)\t \tHydrogen gas is liberated in both the test tubes. \t\t\t(ii)\t When we bring a burning candle near the evolving gas, it burns with a pop sound. This proves that the produced gas is hydrogen gas. \t\t(d)\tMg + H2SO4 \u2192 MgSO4 + H2 \t\t\tMg + H2CO3 \u2192 MgCO3 + H2 \t\t(e)\tH2SO4 has lower pH value and H2CO3 has lower H+ concentration. \t 4.\t (a)\t Metal carbonate and hydrogen carbonate react with acids to give corresponding salt, carbon dioxide and water.","76 ANSWER KEY \t \t (b)\t(i)\t Metal carbonate : \t\t\t\tNa2CO3(s) + 2HCl(aq) \u2192 2NaCl(aq) + H2O(l) + CO2(g) \t\t\t(ii)\t Metal hydrogen carbonate : \t\t\t\tNaHCO3(s) + HCl(aq) \u2192 NaCl(aq) + H2O(l) + CO2(g) \t \t (c)\tGas evolved is carbon dioxide (CO2). \t \t (d)\tWhen this gas is passed through lime water, it turns milky. \t 5.\t (a)\tA : Hydrated copper sulphate \t\t\tB : Water of crystallisation \t\t\tC : Anhydrous copper sulphate \t\t\tD : Water \t\t(b)\t CuSO4.5H2O \uf8e7H\uf8e7eat\uf8e7\u2192 CuSO4 + 5H2O (Blue) (White) \t\t\tCuSO4 + 5H2O \uf8e7\u2192 CuSO4.5H2O ` (White) (Blue) \t\t(c)\tOne other salt which also shows the same property is gypsum (CaSO4.2H2O). \t 6.\t (a)\t\tChemical name-Sodium carbonate. \t\t\tFormula - Na2CO3.10H2O \t\t(b)\tNaCl + H2O + CO2 + NH3 \u2192 NH4Cl + NaHCO3 \t\t \t2NaHCO3 \uf8e7A\uf8e7\uf026\uf026 \u2192 Na2CO3 + CO2 \u2191 + H2O \t\t\tNa2CO3 + 10H2O \uf8e7\u2192 Na2CO3.10H2O. \t\t(c)\tIt is a basic salt because when dissolves in water it gives a strong base NaOH. \t\t\t(i)\t In glass, paper industry. \t\t\t(ii)\t As cleansing agent. \t\t\t(iii)\t For removing permanent hardness. (any one) \t 7.\t (a)\t\tHydrochloric acid and sodium hydroxide. \t\t\tNaCl, sodium chloride, ocean water. \t\t(b)\tDeposits of solid salt are found in several parts of the world. These large crystals are called rock salt. \t\t\tBrown, due to impurities. \t\t(c)\t2NaCl + 2H2O \uf8e7E\uf8e7lect\uf8e7ricit\uf8e7y\u2192 2NaOH + Cl2 + H2 APPLICATION BASED QUESTIONS (Self-Practice) \t1.\tBasic salt : \t\t(i)\tBase - KOH (potassium hydroxide). \t\t\tAcid - H2SO4 (sulphuric acid). \t\t(ii)\tBase - NH4OH (ammonium hydroxide). \t\t\tAcid - HCl (hydrochloric acid). \t2.\tCompound \u2018A\u2019 is sodium carbonate and the gas evolved is CO2. \t \tNa2CO3(s) + dil. H2SO4(l) \uf8e7\u2192 Na2SO4(s) + CO2(g) + H2O(l) \t\t(A)","ANSWER KEY 77 \t3.\t (i)\tLower the pH of the solution, more is the Hydrogen ion concentration. Thus, solution A (pH = 6) has more hydrogen concentration as compared to solution B(pH = 8). \t\t(ii)\tSolution A is acidic while solution B is basic. \t4.\tAqueous solution of sodium chloride is neutral because it is formed from strong acid (HCl) and strong base (NaOH). \t\t Aqueous solution of sodium forms sodium hydroxide, which is basic in nature. \t\t\t\t\t2Na + 2H2O \uf8e7\u2192 2NaOH + H2 \t5.\t (a)\tAs base, to neutralise the ant stung area. \t \t (b) \tWhen baking powder is heated or mixed in water; Baking soda (NaHCO3) reacts with tartaric acid to release CO2 gas. \t\t\tNaHCO3 + H+ \u2192 + H2O + sodium salt of acid \t\t\tCO2 gas make the bread or cake soft and spongy \t \t (c) \tTo produce CO2 gas which extinguish the fire. \t6.\tStrong electrolytes are those which dissociated into ions completely in aqueous solution, e.g., molten NaCl and dilute HCl. \t\tWeak electrolytes are those which do not dissociate into ions completely in aqueous solution, e.g., CH3COOH, NH4OH \t7.\tCurry contains turmeric which acts as acid - base indicator. Soap is basic in nature. Turmeric turns reddish brown in basic medium. On washing with plenty of water reddish brown colour is removed and yellow turmeric is left. \t8.\t (a)\t\tDil. hydrochloric acid reacts with magnesium to form magnesium chloride and H2 gas is liberated. \t\t\tMg(s) + 2HCl(aq) \uf8e7\u2192 MgCl2(aq) + H2(g) \t\t(b) \tReaction between dil. hydrochloric acid and sodium hydroxide is a neutralisation reaction. Sodium chloride salt and water are formed. \t\t\tNaOH(aq) + HCl(aq) \uf8e7\u2192 NaCl(aq) + H2O(l) \t\t(c) \tEgg shells are made of calcium carbonate, CaCO3. Dilute hydrochloric acid dissolves the CaCO3 and makes the shell soft. \t\t\tCaCO3(s)+HCl(aq)\u2192CaCl2 + CO2(g)+ H2O(l) \t \t\t (crushed egg shell) \t9.\t (a)\tSubstance \u2018X\u2019 is lime water [Ca(OH)2]. \t\t\tCa(OH)2(aq) + CO2(g) \uf8e7\u2192 CaCO3(s) + H2O(l) \t\t\t\t\t(white precipitate) \t\t(b)\tLime water can be obtained from CaO (quick lime). \t\t\tCaO(s) + H2O (l) \uf8e7\u2192 Ca(OH)2 \t \t\t\t (Lime water) ANALYZING, EVALUATING & CREATING TYPE QUESTIONS (Self-Practice) \t1.\t (i)\tIt is written in this form because two formula units of CaSO4 share one molecule of water. \t\t(ii) \tSodium hydrogen carbonate being alkaline, neutralises excess acid in the stomach and provides relief.","78 ANSWER KEY \t\t(iii)\tThe process is called chlor-alkali because of the products formed-chlor for chlorine and alkali for sodium hydroxide. \t2.\t (i)\t\tThe dilution of a concentrated acid is a highly exothermic reaction. If water is added to a concentrated acid, then the heat generated may cause the mixture to splash out and cause burns. \t\t(ii) \tCompounds like alcohol and glucose do not dissociate to form hydrogen ions (H+) when dissolved in water and thus do not show any acidic behaviour. \t3.\tTap water contains many of the dissolved salts which dissociate into ions when electricity is passed. These ions conduct electricity, whereas distilled water does not contain any dissolved salts. \t4.\tDry hydrogen chloride gas does not contain H+ ions as acids produce hydrogen ions H+ (aq) in solution which are responsible for acidic properties of acids.","ANSWER KEY 79 CHAPTER 03 METALS AND NON-METALS ASSERTIONS AND REASONING TYPE QUESTIONS (Self-Practice) \tI.\t 1.\t (b)\t 2.\t(b)\t 3.\t(a) 4.\t(a) \t\t4.\t(b)\t 5.\t(b) \tII.\t 1.\t (a)\t 2.\t(c)\t 3.\t(d)\t \t\t5.\t(b)\t 6.\t(d)\t 7.\t(b) QUESTION BANK Short Answer Type Questions (3 Marks) \t1.\tSodium chloride when dissolves in water ionises into its respective ions (Na+). So, due to polar nature sodium chloride is soluble in water. \t\t But ionic compounds (having strong ionic attraction) are not soluble in organic solvent like kerosene oil, benzene, ethanol etc. because ionic compound are not ionised in kerosene oil. \t 2.\t (i)\t\tAluminium does not corrode easily because on exposure to air, its surface is coated with a thin layer of aluminium oxide which is protective and non-reactive. \t\t(ii)\tIt is because copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat. \t3.\tIonic compounds are formed in these compounds. \t\t The general properties of ionic compounds are: \t\t(i)\tSolid \t\t(ii)\tHigh melting and boiling point \t\t(iii)\tSoluble in water \t\t(iv)\tGood conductor of electricity \t4.\tActivity: In a test tube, a small amount of salt solution of P is taken and metal Q is added into it. Q being more reactive, displaces metal P from its salt solution. \t\tChemical equation: \t\t Metal Q + Salt solution of P \u2192 Salt solution of Q + Metal P. 5. Roasting Calcination \t 1.\t In this the ore is heated in the presence of excess \t 1.\t In this the ore is heated in the absence of excess of air. of air.\t \t 2.\t It is done for sulphide ores. \t 2.\t It is done for carbonate ores. \t 3.\tSO2 gas is evolved. \t 3.\tCO2 gas is evolved. \t 4.\t 2MS + 3O2 \uf8e7h\uf8e7eat\uf8e7\u2192 2MO + 2SO2 \t 4.\tMCO3 \uf8e7h\uf8e7eat\uf8e7\u2192 MO + CO2 \t6.\tHgS \u2013 Cinnabar. \t\t First, HgS is converted into HgO. \t\t 2HgS + 3O2 \uf8e7\u2206\uf8e7\u2192 2HgO + 2SO2 \t \t Then, HgO is reduced to mercury on further heating. \t\u2003\u2003 2HgO \uf8e7\u2206\uf8e7\u2192 2Hg + O2","80 ANSWER KEY \t 7.\t (i)\tMetals have electrons which are free to move. \t\t(ii)\tA non-metal is an electron acceptor. It cannot supply electrons to H+ ions. Hydrogen can only be displaced from dilute acids if electrons are supplied to the H+ions of the acid. \t\t(iii)\tThe layer of aluminium oxide formed prevents the metal from further oxidation. \t8.\t (a)\tNa reacts with cold water. \t\t\t2Na(s) + 2H2O(l) \u2192 2NaOH(aq) + H2(g) \t\t\t Cold \t\t(b)\tMg reacts with hot water. \t\t\tMg(s) + H2O(l) \u2192 Mg(OH)2(aq) + H2(g) \t\t\t Hot \t\t(c)\tFe reacts with steam. \t\t\tFe(s) + 4H2O(g) \u2192 Fe3O4(s) + 4H2(g) \t\t \t Red Hot Steam \t9.\t (a)\tCalcium phosphate Ca3(PO4)2 is found in bone. \t\t\tSo, X = Calcium \t\t\tOxide of X = Calcium oxide (CaO), which is used extensively in the cement industry. \t\t\tCaO + 2H2O \u2192 Ca(OH)2 + H2\u2191 \t\t Calcium hydroxide \t\t(b)\tMagnesium reacts only with hot water. Product formed is magnesium hydroxide. \t\t\tMg + 2H2O \u2192 Mg(OH)2 + H2\u2191 \t\t Magnesium hydroxide 10. Metals Non-metals \t 1.\t Burn in air to form metal oxides which are basic \t 1.\t Burn in air to form non-metal oxides which are in nature. acidic in nature. \t 2.\t React with acids to form salt and hydrogen. \t 2.\tThey are electron acceptors so cannot produce hydrogen from acids. \t 3.\t Metals form compounds with non-metals which are ionic. \t 3.\tNon-metals form compounds with non-metals which are covalent. \t\te.g., NaCl \t\te.g., CCl4 \t 11.\t (i)\tIron does not burn in` air even on strong heating. At high temperature, it combines with oxygen of the air to form Fe3O4. \t\t\t3Fe + 2O2 \uf8e7H\uf8e7eat\uf8e7\u2192 Fe3O4 Iron (II, III) oxide \t\t(ii)\tCalcination of lead carbonate. Heating the ore in absence of air. \t\t\tPbCO3(s) \uf8e7H\uf8e7eat\uf8e7\u2192 PbO(s) + CO2(g) \t\t(iii)\tCr2O3(s) + Al(s) \u2192 Al2O3(s) + 2Cr(l) \t\t\tChromium is obtained in molten form. \t 12.\t (a)\tMost reactive element is \u2018B\u2019 as it has replaced both \u2018A\u2019 and \u2018C\u2019 from their compounds. \t\t(b)\tElement \u2018C\u2019 is least reactive as it has been replaced by both \u2018A\u2019 and \u2018B\u2019. \t\t(c)\tDisplacement reaction.","ANSWER KEY 81 \t 13.\t (i)\t Due to strong force of attraction between the positive and negative ions, ionic compounds are solids. These compounds are generally brittle and break into pieces when pressure is applied. \t\t(ii)\tIonic compounds are generally soluble in water. \t\t(iii)\t Ionic compounds in the solid state do not conduct electricity but in aqueous and molten state, they do conduct electricity. \t 14.\t (a)\tSodium cannot be obtained from its oxide by heating with carbon because carbon cannot reduce the oxides of sodium. \t\t(b)\tSodium can be obtained from sodium chloride by the process of electrolytic reduction. \t 15.\t (i)\tThe insoluble impurities which settle down at the bottom of the anode are known as anode mud. \t\t\tCathode is made of pure metal. \t\t(ii)\t At anode: Cu(s) \u2192 Cu2+(aq) + 2e\u2013 \t\t\tAt cathode: Cu2+(aq) + 2e\u2013 \u2192 Cu(s) \t 16.\t \uf077\tCopper, zinc. \t\t\uf077\tImpure metal is made the anode and thin strip of pure metal is made the cathode. A solution of the metal salt is used as an electrolyte. \t\t\uf077\tPure metal from the electrolyte is deposited on the cathode. \t 17.\t (a)\t(i) Thermite reaction, (ii) Redox reaction. \t\t(b)\tOxidation means addition of oxygen to a substance or removal of hydrogen from a substance. \t\t\tAluminium is oxidised. \t\t\tFe2O3 is oxidising agent. \t18.\tThe reaction which is highly exothermic and in which metal is produced in molten state is known as thermit reaction. Consider the following displacement reaction: \t\tFe2O3(s) + 2Al (s) \uf8e7H\uf8e7eat\uf8e7\u2192 Al2O3(s) + 2Fe(l) + Heat \t\t In this reaction, when iron (III) oxide (Fe2O3) is heated with aluminium powder (Al), the amount of heat evolved is so large that the metal iron (Fe) is produced in molten state. Hence, this reaction is used to join railway tracks or cracked machine parts. \t 19.\t (a)\t \t\t(b)\t(i)\tCation is positively charged [Mg2+]. \t\t\t(ii)\tAnion is negatively charged (O2\u2013). \t\t(c) \tA solution of ionic compounds contain ions since electricity conduction requires movement of charged particles they conduct electricity. \t\t\t(i) \tSoluble in water. \t\t\t(ii) \tGood conductor of electricity in molten state and aqueous solution. \t\t\t(iii) \tHigh melting and boiling point. \t 20.\t (a)\tAluminium is covered with a strong protective layer of oxide which does not peel off easily and thus, protects the metal from further corrosion. \t\t(b) \tNitric acid is a strong oxidising agent. It oxidises the hydrogen produced to water and itself gets reduced to any of the oxide of nitrogen. \t\t(c) \tBecause aluminium has greater affinity for oxygen than for carbon, i.e., carbon cannot reduce alumina (Al2O3) to aluminium.","82 ANSWER KEY \t 21.\t (a)\t\tCalcium starts floating when added to water because the bubbles of hydrogen gas formed stick to the surface of the metal and makes it lighter. \t\t(b)\tHNO3 is a strong oxidising agent. It oxidises H2 to H2O. \t\t(c)\t3Fe + 4H2O \u2192 Fe3O4 + 4H2 \t\t\tThe compound is ferroferric oxide (Fe3O4). \t22.\tAlloys are homogeneous mixture of two or more metals or a metal and a non-metal that cannot be separated into their components by physical methods. \t\t(i)\tThe electrical conductivity, and \t\t(ii)\tMelting point of an alloy is less than that of pure metal. \t\t\te.g., (a)\tBrass and bronze (an alloy of Cu) are not good conductors of electricity, whereas copper is used in making electrical circuit. \t\t\t(b) S\t older has a low melting point. \t 23.\t (a)\tMagnesium (Mg) and manganese (Mn). \t \t (b)\t This is because these metals have more affinity for oxygen than carbon. \t \t (c)\tIt forms sodium hydroxide. \t\t\t2Na + 2H2O \uf8e7\u2192 2NaOH + H2 \t 24.\t (a)\t It is because it is easier to obtain a metal from its oxide, as compared to its sulphide and carbonates. \t \t (b)\t(i) Magnesium (ii) Copper. \t 25.\t (a)\t Iron (Fe), aluminium (Al) and zinc (Zn) do not react either with cold or hot water. They react with steam to form metal oxide and hydrogen, e.g., \t\t 3Fe(s) + 4H2O(g) \uf8e7\u2192 Fe3O4(s) + 4H2(g) \t \t (b)\t(i) Caesium\t\t(ii) Gallium. \t 26.\t (a)\tIodine is a non-metal which is lustrous. Iron is a metal which is non-lustrous. \t\t(b)\t4Al + 3O2 \u2192 2Al2O3 \t\t (Aluminium oxide) \t \t (c)\tMovement of ions in the solid state is not possible due to their rigid structure. \t 27.\t \uf06c\tIron is more reactive than copper. \t\t\uf06c\t When CuSO4 solution is kept in iron pot, Fe being more reactive than Cu, it displaces Cu of CuSO4 to form Cu as metal and FeSO4 is formed. \t\t\uf06c\tSince Fe is taking part in the reaction, it comes out from the iron pot forming holes in the pot. \t\t\tCuSO4 + Fe \u2192 FeSO4 + Cu \t 28.\t (i)\t The compounds formed by the transfer of electrons from a metal to a non-metal are known as ionic compounds or electrovalent compounds. \t\t(ii)\tBecause movement of ions in the solid is not possible due to their rigid structure. Long Answer Type Questions (5 Marks) \t 1.\t (a)\t(i)\t Concentration of ore: By gravity separation method or hydraulic washing. \t\t\t(ii)\t Conversion of ore into metal oxide: By calcination method. \t\t\t\te.g.,\t ZnCO3(s) \uf8e7C\uf8e7alHc\uf8e7ineaatti\uf8e7on\u2192 ZnO(s) + CO2(g) \t\t\t(iii)\t Reduction of metal oxide to metal: Metals of middle of the reactivity series are moderately reactive and hence can be reduced by using carbon.","ANSWER KEY 83 \t\t\t\tZnO(s) + C(s) \uf8e7\u2192 Zn(s) + CO(g) \t\t(b) \t(i)\t Concentration of an ore: By froth floatation process. \t\t\t(ii)\t Conversion of ore into metal oxide: By roasting method. \t\t\t\tCu2S(s) + 3O2(g) \uf8e7R\uf8e7oHaes\uf8e7taitng\uf8e7\u2192 2Cu2O + 2SO2(g) \t\t\t(iii)\t Reduction of metal oxide to metal: Copper being less reactive can be reduced by heat alone \t\t\t\tCu2O(s) + Cu2S(s) \uf8e7H\uf8e7eat\uf8e7\u2192 6Cu(l) + SO2(g) \t\t\t\t Electrolytic refining of copper. \t 2.\t (a)\tCarbonate ores are calcined. \t\t\te.g., MCO3 \uf8e7H\uf8e7eat\uf8e7\u2192 MO + CO2 \t\t(b)\tCalcined ore is obtained in oxide form. \t\t\t\tIt can be reduced into metal by reduction process. \t\t\te.g., 2MO + C \u2192 2M + CO2 \t\t(c)\tNa, Ca, Al, Mn (any two). \t 3.\t (a)\t\tAs the ore gives SO2 on heating, it is sulphide ore. \t\t\tSteps of metallurgy: \t\t\t(i)\t Concentration of ore by froth floatation process. \t\t\t(ii)\t Conversion of sulphide ore into oxide by roasting. \t\t\t(iii)\t Conversion of metal oxide to metal either by heating alone or by reduction with carbon. \t\t(b)\tZn(s) + CuSO4(aq) \u2192 ZnSO4(aq) + Cu(s) \t\t\t Yes, because Zn is more reactive than copper so will displace copper from copper sulphate solution. \t\t\tFe(s) + ZnSO4(aq) \u2192 FeSO4(aq) + Zn(s) \t\t\tNo, because Fe is less reactive than Zn. \t 4.\t (i)\tSodium,\t (ii)\tMercury,\t (iii)\tGallium,\t (iv)\tIodine, \t\t(v)\tCarbon. \t 5.\t (i)\t Calcium starts floating because the bubbles of hydrogen gas formed stick to its surface. \t\t\tCa(s) + 2H2O(l) \uf8e7\u2192 Ca(OH)2(aq) + H2(g) \t\t(ii)\tIn dry air, sodium forms sodium peroxide. \t\t\t4Na(s) + O2(g) \uf8e7\u2192 2Na2O2(s) (Sodium peroxide) \t \t\t\t \t\t\t If the air is moist and contains a lot of water, sodium reacts violently with the water content of air and forms sodium hydroxide and hydrogen gas, producing a lot of heat \t\t\t2Na(s) + 2H2O(l) \u2192 2NaOH(s) + H2(g) + Heat","84 ANSWER KEY \t\t(iii)\tIron displaces copper from copper sulphate solution. \t\t\tFe + CuSO4 \uf8e7\u2192 FeSO4 + Cu \t\t(iv)\tPotassium reacts violently with cold water. \t\t\t2K(s) + 2H2O(l) \uf8e7\u2192 2KOH(aq) + H2(g) + Heat energy \t\t(v)\tCarbonic acid is formed. \t\t\tCO2 + H2O \u2192 H2CO3 \t 6.\t (i)\t \tZn + H2SO4 \u2192 ZnSO4 + H2 \t\t(ii)\tZn + 2HCl \u2192 ZnCl2 + H2 \t\t(iii)\tZn + AlCl3 \u2192 No reaction \t\t(iv)\tZn + 2NaOH \u2192 Na2ZnO2 + H2 \t\t(v)\tZn + 4HNO3 \u2192 Zn(NO3)2 + 2NO2 + 2H2O \t 7.\t (i)\tIonic compounds have high melting and boiling points because a considerable amount of energy is required to break the strong interionic attraction. \t \t (ii)\tIonic compounds are soluble in water because their oppositely charged ions break by the opposite pole of water molecules. \t \t (iii)\t They are solids and are somewhat hard because of the strong force of attraction between the positive and negative ions. \t \t (iv)\tIonic compounds conduct electricity in molten state because the electrostatic forces of attraction between the oppositely charged ions are overcome due to heat. \t\t(v)\t Metals lose electrons as a tendency to attain a completely filled valence shell. \t 8.\t(i)\tThey are shiny and unreactive. \t\t(ii)\tCopper is lesser reactive than hydrogen. \t\t(iii)\tAs it is an alloy. \t\t(iv)\tMalleable and ductile. \t\t(v) \tAs HNO3 is a strong oxidising agent and oxidises H2 to H2O. \t 9.\t(a)\t Mg has more affinity for oxygen than for carbon. \t\t(b)\tElectrolytic reduction process. \t\t\tAt cathode: 2Na+ + 2e\u2013 \u2192 2Na \t\t\tAt anode: 2Cl\u2013 \u2192 Cl2 + 2e\u2013 \t\t(c)\t2Cu2S + 3O2 \u2192 2Cu2O + 2SO2 \t\t\t2Cu2O + Cu2S \u2192 6Cu + SO2 \t 10.\t (a)\tSilver sulphide (Ag2S), copper carbonate (CuCO3). \t\t(b)\tGalvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc. The galvanised article is protected against rusting even if the zinc coating is broken. \t\t(c)\t Alloy is a homogeneous mixture of two or more metals or a metal and non-metal. It is prepared by first melting the primary metal and then dissolving the other elements in it in definite proportion. It is then cooled to room temperature. \t\t\t\t (i)\tOn mixing carbon, it becomes hard and strong. \t\t\t\t(ii)\tOn mixing Ni, and Cr, it becomes hard and does not rust.","ANSWER KEY 85 \t 11.\t (i)\t(a) \t2Cu2S + 3O2 \uf8e7h\uf8e7eat\uf8e7\u2192 2Cu2O(s) + 2SO2(g) \t\t\t(b) \t2Cu2O + Cu2S \uf8e7h\uf8e7eat\uf8e7\u2192 6Cu(s) + SO2(g) \t\t(ii)\tRemoval of impurities from the metals after their reduction. \t\t\tAnode: impure copper \t\t\t \t\t\tCathode: pure copper \t\t\t Electrolyte: acidified CuSO4 \t 12.\t (a)\t Copper (Cu) and Mercury (Hg) \t\t(b) Calcination Roasting \t 1.\t Zinc carbonate is heated in limited supply of air. \t 1.\t Zinc sulphide is heated in excess of air. \t\tZnCO3 \uf8e7\u2206\uf8e7\u2192 ZnO + CO2 \t\t 2ZnS + 3O2 \uf8e7\u2206\uf8e7\u2192 2ZnO + 2SO2 \t\t(c)\tThermit reaction between iron (III) oxide and aluminium powder. \t\t\tFe2O3 (s) + 2Al (s) \u2192 2Fe(l) + Al2O3 (s) + heat \t\t\t Significance: \t\t\t\uf06c It is highly exothermic reaction. \t\t\t\uf06c I\tron is obtained in molten form. APPLICATION BASED QUESTIONS (Self-Practice) \t 1.\t (a)\tMetals are reactive in nature. They form oxides, sulphides, selerides, halides, carbonates, sulphates etc. easily so they are not found in their free states. \t\t(b)\t Metals are good conductor of heat due to presence of free electrons. So, the conduction of heat takes place easily. \t2.\tA is a non-metal because non-metal oxides are acidic or neutral in nature. \t\t AO = CO (Carbon mono oxide) \u2013 Neutral oxide \t\tAO2 = CO2 (Carbon dioxide) \u2013 Acidic oxide \t 3.\t (a)\tOxides of metals are mostly basic in nature. Water soluble basic oxide is known as alkali. \t\t(b)\tSome metals like magnesium, aluminium, zinc etc., when exposed to air, form protective layer of oxide on their surface. This layer prevents further corrosion of the metal. \t\t(c)\t Due to high electropositive nature alkalis of some metals are soft. They can be cut with the help of a knife, e.g., Li (Lithium), Na (Sodium), K (Potassium). \t 4.\t (i)\t Electrolytic reduction: It is a process of obtaining metals from their molten chlorides or molten oxides by electrolysis. The metals are deposited at the cathode whereas chlorine or oxygen is liberated at anode.","86 ANSWER KEY \t\t \t Electrolytic refining: It is a process of refining of impure metals obtained by any of the reduction processes. The impure metal is taken as anode, pure metal as cathode and metal salt solution as electrolyte. \t\t(ii)\t Minerals are the elements or compounds which occur naturally in the earth\u2019s crust. Ores are the minerals from which metals can be extracted profitably. \t\t(iii)\t Alloy is a homogeneous mixture of two or more metals or a metal and a non-metal. Amalgam is an alloy in which one of the metals is mercury. \t5.\tSulphur(S) is a non-metal \t \t 1.\tSulphur is a brittle and has low melting and boiling point. \t\t 2.\tSulphur forms electronegative (S2\u2013) ion and is a bad conductor of heat and electricity. \t\t 3.\tSulphur burns in air to form acidic oxide which gets dissolved in water to form an acid. \t\t\t(a) S(s) + O2 (g) \u2192 SO2(g) \t\t\t Acidic oxide \t\t\t(b) SO2(g) + H2O (l) \u2192 H2SO3 (aq) \t\t\t Acid \t \t\tNote: All the above properties are shown by a non-metal only, thus proving sulphur to be a non- metal. \t\t \t Magnesium (Mg) is a metal \t\t\t1.\tMagnesium is hard and has high melting and boiling point. \t\t\t2. \tMagnesium forms electropositive (Mg2+) ion and is a good conductor of heat and electricity. \t\t\t3. M\t agnesium burns in air to form basic oxide which gets dissolved in water to form a base. \t\t\t(a) 2\t Mg(s) + O2(g) \u2192 2MgO(s) \t\t\t\t(b) MgO(s) + H2O(l) \u2192 Mg(OH)2(aq) \t \t\t Base \t\t\tAll the above properties are shown by a metal only, thus proving magnesium to be a metal. \t 6.\t (a)\t We can store copper sulphate in silver vessel (container) because silver is less reactive than copper. So, displacement reaction does not occur. \t\t\t But we cannot store silver nitrate solution in copper container because copper is more reactive than silver. So it displaces silver from its salt. \t\t\tCu + 2Ag(NO3)2 \u2192 Cu(NO3)2 + 2Ag \t\t(b)\tNitric acid (HNO3) is a strong oxidising agent. It oxidised the produced hydrogen to water and itself reduced to (NO, NO2, N2O). \t\t(c)\tTin is less reactive metal than zinc. So it is not easily attacked by components of food items. ANALYZING, EVALUATING & CREATING TYPE QUESTIONS (Self-Practice) \t 1.\t (i) \tMetals conduct electricity because they have electrons which are free to move. Thus, they offer little resistance to the flow of current. \t\t(ii) \tThe reaction of iron (III) oxide (Fe2O3) with heated aluminium is highly reactive. The amount of heat evolved is so large that the iron metal is produced in the molten state. For this reason, this reaction is used to join cracked machine parts.","ANSWER KEY 87 \t\t\tFe2O3(s) + \t2Al(s) \uf8e7H\uf8e7eat\uf8e7\u2192 2Fe(l) + Al2O3(s) \t\t\tIron(III) oxide Aluminium\t Molten iron Aluminium oxide \t\t(iii) \tThere are two reasons for this: \t\t\t(a)\t These metals are very reactive and may even catch fire when they come in contact with oxygen of the air. \t\t\t(b)\t These metals can also combine with moist air containing carbon dioxide and further forming a carbonate layer on metal surface. \t 2.\t (i) \tWhen a metal is heated, its atom gain energy and vibrate more vigorously. This energy is transferred to the electrons, which can move through the metal. They transfer their energy to other electrons and atoms. In this way, metals conduct heat and thus, are good conductors of heat. \t\t(ii) \tPure gold (known as 24 carat gold) is very soft. It is, therefore, not suitable for making jewellery. It is alloyed with either silver or copper to make it hard. \t\t(iii) \tA non-metal is an electron acceptor. It cannot supply electrons to H+ ions. Therefore, it does not displace hydrogen from dilute acids.","NOTES"]


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