Comprehensive CBSE Objective Type Question Bank Chemistry (Term -1)

CBSE Objective Type Question Bank Chemistry Features TERM—I - Strictly Based on the Latest CBSE Term-wise Syllabus Multiple Choice Questions (MCQs) Assertion-Reason Type Questions Matching Type Questions Very Short Answer Type Questions Fill in the Blanks True or False Statements Case Study Based MCQs CLASS 12



Comprehensive CBSE Objective Type Question Bank Chemistry Term–I (For Class XII)



Comprehensive CBSE Objective Type Question Bank Chemistry Term–I (FOR CLASS XII) (According to the Latest CBSE Examination Pattern) By Dr. N.K. VERMA Dr. N.K. SHARMA Formerly, Associate Professor Nutan Vidya Mandir Chemistry Department Dilshad Garden D.A.V. College Delhi Chandigarh   LAXMI PUBLICATIONS (P) LTD (An ISO 9001:2015 Company) BENGALURU • CHENNAI • GUWAHATI • HYDERABAD • JALANDHAR KOCHI • KOLKATA • LUCKNOW • MUMBAI • RANCHI NEW DELHI

Comprehensive CBSE OBJECTIVE TYPE QUESTION BANK CHEMISTRY–XII Copyright © by Laxmi Publications Pvt., Ltd. All rights reserved including those of translation into other languages. In accordance with the Copyright (Amendment) Act, 2012, no part of this publication may be reproduced, stored in a retrieval system, translated into any other language or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise. Any such act or scanning, uploading, and or electronic sharing of any part of this book without the permission of the publisher constitutes unlawful piracy and theft of the copyright holder’s intellectual property. If you would like to use material from the book (other than for review purposes), prior written permission must be obtained from the publishers. Printed and bound in India Typeset at: Goswami Associates, Delhi New Edition ISBN : 978-93-5274-540-1 Limits of Liability/Disclaimer of Warranty: The publisher and the author make no representation or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties. The advice, strategies, and activities contained herein may not be suitable for every situation. In performing activities adult supervision must be sought. Likewise, common sense and care are essential to the conduct of any and all activities, whether described in this book or otherwise. Neither the publisher nor the author shall be liable or assumes any responsibility for any injuries or damages arising here from. The fact that an organization or Website if referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Website may provide or recommendations it may make. Further, readers must be aware that the Internet Websites listed in this work may have changed or disappeared between when this work was written and when it is read. All trademarks, logos or any other mark such as Vibgyor, USP, Amanda, Golden Bells, Firewall Media, Mercury, Trinity, Laxmi appearing in this work are trademarks and intellectual property owned by or licensed to Laxmi Publications, its subsidiaries or affiliates. Notwithstanding this disclaimer, all other names and marks mentioned in this work are the trade names, trademarks or service marks of their respective owners. Bengaluru 080-26 75 69 30 Chennai 044-24 34 47 26 Branches Guwahati 0361-254 36 69 Hyderabad 040-27 55 53 83 Jalandhar 0181-222 12 72 Kochi 0484-405 13 03 Kolkata 033-40 04 77 79 Lucknow 0522-430 36 13 Published in India by Ranchi 0651-224 24 64 Laxmi Publications (P) Ltd. C—00113/021/07 Printed at : First Impression, Noida. (An ISO 9001:2015 Company) 113, GOLDEN HOUSE, GURUDWARA ROAD, DARYAGANJ, NEW DELHI - 110002, INDIA Telephone : 91-11-4353 2500, 4353 2501 www.laxmipublications.com [email protected]

Contents 1. The Solid State ................................................................................ 1–11 2. Solutions ........................................................................................ 12–28 3. p-Block Elements .......................................................................... 29–44 4. Haloalkanes and Haloarenes ....................................................... 45–59 5. Alcohols, Phenols and Ethers ....................................................... 60–74 6. Biomolecules ................................................................................. 75–88



Syllabus CLASS XII TERM-I EVALUATION SCHEME THEORY S.No. Units Periods Marks 1 10 2 Solid State 8 10 3 4 Solutions 8 15 5 6 p-Block Elements 7 35 Haloalkanes and Haloarenes 9 Alcohols, Phenols and Ethers 9 Biomolecules 8 TOTAL 49 Solid State: Classification of solids based on different binding forces: molecular, ionic, covalent and metallic solids, amorphous and crystalline solids (elementary idea). Unit cell in two dimensional and three dimensional lattices, calculation of density of unit cell, packing in solids, packing efficiency, voids, number of atoms per unit cell in a cubic unit cell, point defects. Solutions: Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions, Raoult's law, colligative properties – relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties. p-Block Elements: Group-15 Elements: General introduction, electronic configuration, occurrence, oxidation states, trends in physical and chemical properties; Nitrogen preparation, properties and uses; compounds of Nitrogen: preparation and properties of Ammonia and Nitric Acid. Group-16 Elements: General introduction, electronic configuration, oxidation states, occurrence, trends in physical and chemical properties, dioxygen: preparation, properties and uses, classification of Oxides, Ozone, Sulphur – allotropic forms; compounds of Sulphur: preparation, properties and uses of Sulphur-dioxide, Sulphuric Acid: properties and uses; Oxoacids of Sulphur (Structures only).

Group-17 Elements: General introduction, electronic configuration, oxidation states, occurrence, trends in physical and chemical properties; compounds of halogens, Preparation, properties and uses of Chlorine and Hydrochloric acid, interhalogen compounds, Oxoacids of halogens (structures only). Group-18 Elements: General introduction, electronic configuration, occurrence, trends in physical and chemical properties, uses. Haloalkanes and Haloarenes: Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions. Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only). Alcohols, Phenols and Ethers: Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration. Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophillic substitution reactions, uses of phenols. Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses. Biomolecules: Carbohydrates: Classification (aldoses and ketoses), monosaccahrides (glucose and fructose), D-L configuration Proteins: Elementary idea of – amino acids, peptide bond, polypeptides, proteins, structure of proteins – primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins. Nucleic Acids: DNA and RNA

Unit 1: The Solid State  MULTIPLE CHOICE QUESTIONS  In each of the following questions only one option is correct. Select the correct option. 1. The existence of a substance in more than one solid modifications is known as (a) isomorphism (b) polymorphism (c) amorphism (d) allotropy 2. Which of the following is an amorphous solid? (a) Graphite (C) (b) Quartz glass (SiO2) (c) Potash alum [K2SO4 . Al2(SO4)3 . 24H2O] (d) Diamond (C) 3. CO2 molecules are held in the crystals of dry ice by ........ (a) london forces (b) dipole-dipole interactions (c) covalent bonds (d) coulombic forces 4. Which of the following oxides shows electrical properties like metals? (a) SiO2 (b) TiO2 (c) MgO (d) CrO2 5. To get n-type semiconductor, impurity to be added to silicon should have the following number of valence electrons: (a) 2 (b) 3 (c) 1 (d) 5 6. Which of the following statements is not true? (a) Conductivity of semiconductor increases with increase in temperature (b) Pure ionic solids are insulators (c) NaCl is a diamagnetic compound (d) TiO2 is a paramagnetic substance. 7. Which of the following oxides behaves as conductor or insulator depending upon temperature? (a) Ti2O3 (b) SiO2 (c) TiO2 (d) CaO 8. The material used in the solar cells contains ...... (a) Cs (b) Si (c) Sn (d) Ti 9. What is the coordination number in a hexagonal close packed structure in three dimensions? (a) 12 (b) 9 (c) 4 (d) 6 1

2 Chemistry—XII 10. In the cubic close packing, the unit cell has ...... (a) 4 tetrahedral voids each of which is shared by four adjacent unit cells. (b) 8 tetrahedral voids within the unit cell. (c) 8 tetrahedral voids each of the which is shared by four adjacent unit cells. (d) 4 tetrahedral voids within the unit cell. 11. Radius of an octahedral void relative to the radius of the spheres in a close packing is (a) 1.414 (b) 0.225 (c) 1.225 (d) 0.414 12. Among the following types of voids, which is the largest (a) triangular (b) cubic (c) tetrahedral (d) octahedral 13. In a compound, oxide ions have CCP arrangement. Cations A are present in one- eighth of the tetrahedral holes and cations B occupy half the octahedral holes. The simplest formula of the compound is ...... . (a) AB2O4 (b) A2BO4 (c) ABO2 (d) ABO4 14. In a metal M having BCC arrangement, edge length of the unit cell is 400 pm. The atomic radius of ‘M’ is ...... . (a) 200 pm (b) 100 pm (c) 173 pm (d) 141 pm 15. The edge length of the unit cell in terms of the radius of spheres constituting face centred cubic unit cell is ...... . (a) a = 4r (b) a = 4 r (c) a = 2r (d) a = 2 2 r 3 16. Which of the following is a network solid? (a) Dry ice (Solid CO2) (b) I2 (c) Silicon carbide (SiC) (d) H2O (Ice) 17. The total number of octahedral voids in the face centred cubic unit cell is ...... (a) 8 (b) 4 (c) 10 (d) 12 18. The percentage of empty space in a face centred cubic arrangement is ...... (a) 74 (b) 26 (c) 68 (d) 32 In each of the following questions two or more options are correct. Select the correct options. 19. Which of the following are true for quartz glass? (a) It is an amorphous solid. (b) Refractive index is same in all the directions. (c) It has definite heat of fusion. (d) It may be called super-cooled liquid. 20. Which of the following are characteristics of a crystalline solid? (a) Definite and characteristic heat of fusion. (b) Isotropic nature. (c) A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal. (d) Anisotropic nature.

The Solid State 3 21. Which of the following conditions favour the existence of a substance in the solid state? (a) High temperature (b) Low temperature (c) High thermal energy (d) Strong cohesive forces. 22. Which of the following statements are true about amorphous solids? (a) They are anisotropic in nature. (b) On heating they may become crystalline at certain temperature. (c) They may become crystalline on keeping for long time. (d) Amorhous solids have definite melting point. 23. Which of the following unit cells have all their sides equal i.e., a = b = c? (a) Tetragonal (b) Cubic (c) Orthorhombic (d) Rhombohedral. 24. Which of the following arrangements contain octahedral voids? (a) hcp (b) ccp (c) bcc (d) Simple cubic. 25. Which of the following can be regarded as molecular solids? (a) SiC (Silicon carbide) (b) Dry ice (c) Ice (d) NaCl. 26. Which of the following statements are true? (a) Pairing of electrons cancels their magnetic moment in the diamagnetic substances. (b) Paramagnetic substances are weakly attracted by magnetic field. (c) Ferromagnetic substances cannot be magnetised permanently. (d) The domains in ferromagnetic substances are oppositely oriented with respect to each other. 27. Which of the following statements are true about semiconductors? (a) Silicon doped with electron rich impurity behaves as an n-type semiconductor. (b) Silicon doped with Al is p-type semiconductor. (c) Delocalised electrons increase the conductivity of doped silicon. (d) Conductivity of a semiconductor decreases with increase in temperature. 28. Which of the following arrangements show schematic alignment of magnetic moments of ferromagnetic substances? (a) (b) (c) (d) 29. Which of the following statements are true about metals? (a) Valence band may overlap with conduction band. (b) The gap between valence band and conduction band is negligible. (c) The gap between valence band and conduction band is very large. (d) Valence band may remain partially filled.

4 Chemistry—XII Answers 1. (b) 2. (b) 3. (a) 4. (d) 5. (d) 6. (d) 11. (d) 12. (b) 7. (a) 8. (b) 9. (a) 10. (b) 17. (b) 18. (b) 23. (b), (d) 13. (a) 14. (c) 15. (d) 16. (c) 28. (a), (d) 19. (a), (b), (d) 20. (a), (c), (d) 21. (b), (d) 22. (b), (c) 24. (a), (b) 25. (b), (c) 26. (a), (b) 27. (a), (b), (c) 29. (a), (b), (d).  ASSERTION-REASON TYPE QUESTIONS  The following questions consist of two statements one labelled as Assertion A and the other Reason R. Examine both the statements carefully and mark the correct choice according to the instructions given below: (a) if both A and R are correct and R is correct reason of A (b) if both A and R are correct but R is not correct reason of A (c) if A is correct R is wrong (d) if A is wrong R is correct. 1. Assertion A: Quartz glass belongs to the category of ionic solid. Reason R: Quartz glass is supercooled liquid. 2. Assertion A: The packing efficiency is same for hcp and ccp structure. Reason R: The coordination number is 12 in hcp and 8 in ccp. 3. Assertion A: In bcc arrangement coordination number is eight. Reason R: In bcc arrangement atoms occupy cubic voids. 4. Assertion A: Crystalline solids exhibit isotropy. Reason R: The constituent particles in a crystalline solid are arranged in an orderly fashion. 5. Assertion A: bcc arrangement is less closely packed than ccp arrangement. Reason R: In ccp arrangement, the two atoms at the corners of the unit cell are touching each other whereas in bcc arrangement, they are not touching each other. 6. Assertion A: Crystalline solids have sharp melting point. Reason R: Crystalline solids have a regular arrangement of constituent particles. 7. Assertion A: Graphite is a good conductor of electricity. Reason R: Graphite has free valence electrons. Answers 1. (d) 2. (c) 3. (a) 4. (d) 5. (c) 6. (a) 7. (a).

The Solid State 5  MATCHING TYPE QUESTIONS  In the following questions match the items in Column I with the items in Column II. An item in Column I may match with more than one items in Column II. 1. Match the type of unit cell given in Column I with the features given in Column II. Column I Column II (i) Face centred cubic (a) a = b = c (ii) Body centred cubic (b) a  b  c (iii) Simple cubic (c) Number of atoms per unit cell is two (iv) End centred ortho-rhombic (d) Number of atoms per unit cell is four (e) Number of atoms per unit cell is one 2. Match the crystal classes given in Column I with the axial parameters given in Column II. Column I Column II (i) Tetragonal (a) a = b = c (ii) Triclinic (b) a = b  c (iii) Hexagonal (c) a  b  c (iv) Rhombohedral (d)  =  =  = 90° (e)     90° 3. Match the items given in Column I with the items given in Column II. Column I Column II (i) Silicon doped with phosphorus (a) Electronic conductor (ii) Germanium doped with boron (b) Electrolytic conductor (iii) Aluminium metal in solid state (c) n-type semiconductor (iv) Sodium chloride in molten state (d) p-type semiconductor 4. Match the type of packing given in Column I with the coordination numbers given in Column II. Column I Column II (i) Hexagonal close packing in two (a) Coordination number 8 dimensions (b) Coordination number 4 (c) Coordination number 12 (ii) Hexagonal close packing in three (d) Coordination number 6 dimensions (iii) Square close packing in two dimensions (iv) Body centred cubic packing in three dimensions

6 Chemistry—XII 5. Match the compounds in Column I with the items given in Column II. Column I Column II (i) TiO (a) Ferromagnetic (b) Diamagnetic (ii) Fe3O4 (c) Paramagnetic (iii) TiO2 (d) Ferrimagnetic (iv) CrO2 Answers 1. (i)–(a), (d); (ii)–(a), (c); (iii)–(a), (e); (iv)–(b), (c) 2. (i)–(b), (d); (ii)–(c), (e); (iii)–(b); (iv)–(a) 3. (i)–(c); (ii)–(d); (iii)–(a); (iv)–(b) 4. (i)–(d); (ii)–(c); (iii)–(b); (iv)–(a) 5. (i)–(c); (ii)–(d); (iii)–(b); (iv)–(a)  VERY SHORT ANSWER QUESTIONS  1. Explain why amorphous solids are isotropic. 2. What do you understand by anisotropy? 3. Give two examples of amorphous solids. 4. Give any four examples of covalent or network solids. 5. Explain why ionic compounds do not conduct electricity in solid state. 6. Which of the following are molecular solids? Sodium chloride, dry ice, copper, silica, iodine. 7. What is the number of atoms in a unit cell of a metallic crystal having bcc arrangement? 8. Explain why hcp and ccp structures for a particular solid have same density. 9. Out of hcp, ccp and bcc structures, which is the least efficient? 10. How many different types of unit cells are possible for two dimensional lattices? 11. What is the coordination number of each atom in bcc arrangement? 12. What is the number of atoms per unit cell in ccp arrangement? 13. What is the coordination number of each atom in (i) hcp (ii) ccp? 14. What is the packing efficiency of ABCABC...... close packing? 15. How can we change a crystalline substance into its amorphous form? 16. Name the types of voids present in a close packing. 17. What is the packing efficiency of bcc arrangement? 18. In an alloy of gold and cadmium if gold crystallises in cubic structure occupying the corners only and cadmium fits into edge centre voids, what is the formula of the alloy? 19. Metallic potassium crystallizes in bcc type of lattice. How many nearest neighbours does each potassium atom have? 20. If three elements X, Y and O crystallize in a cubic solid lattice with X atoms at the corners, Y atoms at cube centre and O atoms at edges then what is the formula of the solid?

The Solid State 7 21. A metallic element crystallised into a lattice containing a sequence of layers of ABABAB...... . Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space? 22. What is the coordination number of each sphere in cubic close packing of spheres in three dimensions? 23. At what cterymsptaelr,aCtul–reioFnes3hOa4v, ea ferrimagnetic substance, changes to paramagnetic? 24. In NaCl fcc arrangement. What is the number of Cl– ions per unit cell? 25. An atom is present in a cubic void. What is its coordination number? 26. What is the coordination number of an atom present in an octahedral void? 27. What is the maximum possible coordination number of an atom in hcp crystal structure of an element? 28. How many atoms can be assigned to its unit cell if an element forms: (i) a body centred cubic cell? (ii) a face centred cubic cell? 29. What happens when a ferromagnetic substance is heated to high temperature? 30. In a crystal of zinc sulphide, zinc occupies tetrahedral voids. What is the coordination number of zinc? 31. Compare the size of energy gap in conductors, semiconductors and insulators. 32. What is photovoltaic cell? 33. A cubic solid is made of two elements X and Y. Atoms Y are at the corners of the cube and X at the body centre. What is the formula of the compound? 34. How do metallic and ionic substances differ in conducting electricity? 35. What type of interactions hold the molecules together in a polar molecular solid? 36. ‘Crystalline solids are anisotropic in nature’. What does this statement mean? 37. What is meant by the term ‘forbidden zone’ in reference to band theory of solids? 38. What is meant by ‘doping’ in a semiconductor? 39. How may the conductivity of an intrinsic semiconductor be increased? 40. How many atoms constitute one unit cell of a face-centered cubic crystal? 41. What type of substances would make better permanent magnets, ferromagnetic or ferrimagnetic? 42. What is the formula of a compound in which the element Y forms hcp lattice and atoms of X occupy 2 rd of tetrahedral voids? 3 Answers 1. Because the arrangement of particles is irregular in all directions 2. If a solid shows different values of a physical property (such as electrical resistance) when measured along different directions, it is said to possess anisotropy 3. Glass and plastics 4. Silica, diamond, carborundum, graphite

8 Chemistry—XII 5. Because ions are not free to move in solid state 6. Dry ice (solid CO2) and iodine 7. Two 8. Both hcp as well as ccp are equally efficient with coordination number 12 and packing efficiency 74% 9. bcc is the least efficient 10. Five type 11. Eight 12. Four 13. (i) 12 (ii) 12 14. 74% 15. By melting and then cooling suddenly a crystalline substances can be changed into its amorphous form. 16. Tetrahedral and octahedral 17. 68% 18. AuCd3 21. 24% 19. 8 20. XYO3 22. 12 23. 850 K 24. Four 25. 8 26. 6 27. 12 28. (i) 2 (ii) 4 29. It becomes paramagnetic due to randomisation of electron spins 30. 4 31. Conductors < Semiconductors < Insulators 32. A device which directly converts solar energy into electricity 33. XY 34. Metallic substances conduct electricity through movement of electrons while ionic substances conduct electricity through movement of ions. 35. Dipole-dipole 36. It means that the crystalline substances possess different values of physical properties such as refractive index in different directions. 37. Forbidden zone is the region between the valence band and the conduction band. There are no energy states in this region and hence electron cannot be present in this region. 38. The process of adding some impurity to a semiconductor to improve its conductivity is called doping. For example, silicon may be doped with boron or phosphorus. 39. The conductivity of an intrinsic semiconductor can be increased by adding some impurity or by increasing temperature. 40. 4 41. Ferromegnatic substances 42. Y atoms = 12  2  3  6 ; X atoms = 12  2  8 ; Formule = Y6X8 or Y3X4 6 2 1 3  FILL IN THE BLANKS  Fill in the following blanks with appropriate items: 1. Dry ice is an example of ...... solid. 2. In diamond interparticle forces are ...... 3. In hcp arrangement of spheres, the coordination number is ......

The Solid State 9 4. In ccp arrangement of atoms, ...... per cent of the available space remains vacant. 5. In bcc arrangement of atoms, ...... per cent of the available space is occupied by atoms. 6. In rock-salt structure ...... per cent of the octahedral voids are occupied by cations. 7. If the radius ratio r+/r– is 0.325, the cation would most probably be present in a/an ...... void. 8. In CsCl structure the cations are present in ...... voids. 9. In fluorite structure, the coordination number of cations is ...... 10. Glass is an example of ...... solids. 11. The conductivity of semiconductors ...... with the increase in temperature. 12. The conduction through electrons is called ...... conduction. 13. The number of formula units in a CsCl unit cell is equal to ...... 14. The co-ordination number of Na+ in rock-salt structure is ...... 15. In fluorite structure positive ions are arranged in ...... 16. If the radius ratio (r+/r–) is in the range 0.414–0.732, the compound AB is likely to have ...... structure. 17. An atom at the corner of a unit cell makes ...... contribution to a particular unit cell. 18. In zinc blende structure, ...... have ccp arrangement whereas ...... are present in ...... voids. 19. In antifluorite structure, cations are present in ...... voids. 20. The number of formula units per unit cell in fluorite structure is ...... 21. A liquid which is permanently supercooled is frequently called a ...... 22. In the sodium chloride structure each Na+ ion is surrounded by six Cl– ions nearest neighbours and ...... Na+ ions next nearest neighbours. 23. The electrical conductivity of metals is of the order of ...... ohm–1 m–1. 24. Silicon, doped with gallium, behaves as ...... conductor. Answers 1. molecular 2. covalent bonds 3. 12 4. 26 5. 68 6. 100 11. increases 7. tetrahedral 8. cubic 9. 8 10. amorphous 16. rock-salt 20. 4 12. n-type 13. one 14. six 15. CCP 17. 1/8 18. anions; cations; tetrahedral19. tetrahedral 21. glass 22. twelve 23. 104 – 107 24. p-type.  TRUE/FALSE  State whether the following statements are true or false: 1. Na2O has antifluorite structure. 2. S2– ion in zinc blende structure has a coordination number of six. 3. Spinel is a mineral having formula MgAl2O4.

10 Chemistry—XII 4. A compound having radius ratio (r+/r– ) in the range 0.732–1 generally has CsCl structure. 5. Na+, K+ and Rb+ are isoelectronic ions. 6. NaCl is a paramagnetic substance. 7. Diamond is an example of atomic solids. 8. Orthorhombic unit cell has the least symmetry. 9. Cubic unit cell has the highest symmetry. 10. In fluorite structure 50% of the tetrahedral voids are occupied by anions. 11. In zinc blende structure coordination number of cation as well as anion is four. 12. Among the three types of arrangement, hcp, ccp and bcc, the most efficient packing arrangement is bcc. 13. aIfnthocetraahdeidursarlavtoioidr.+/r– is in the range 0.225–0.414 the cation prefers to be present in 14. In rock-salt structure, the number of formula units per unit cell is four. 15. An atom present at the corner of a unit cell contributes one-fourth to a particular unit cell. 16. In end-centred unit cell of an atomic substance there are four atoms per unit cell. 17. TiO2 is paramagnetic. 18. Fe3O4 is ferrimagnetic. 19. In fluorite structure coordination number of cation is 4. Answers 1. True 2. False 3. True 4. True 5. False 6. False 7. False 8. False 11. True 12. False 13. False 14. True 9. True 10. False 17. False 18. True 19. False 15. False 16. False  CASE STUDIES  PASSAGE I Read the passage given below and answer the questions that follow: In zinc blende structures anions are arranged in ccp and cations are present in the tetrahedral voids and only half the tetrahedral voids are occupied. 1. The formula of the compounds having zinc blende structure corresponds to (a) AB2 (b) A2B (c) AB (d) AB3 2. The co-ordination numbers of cation and anion are respectively (a) 4 and 8 (b) 4 and 4 (c) 8 and 4 (d) 8 and 6 3. For this type of structure, radius ratio r+/r– should be in the range (a) 0.225 – 0.414 (b) 0.155 – 0.225 (c) 0.414 – 0.732 (d) 0.732 – 1 4. In this type of lattice, the number of cations per unit cell is (a) 1 (b) 2 (c) 4 (d) 8

The Solid State 11 5. If ‘a’ is the edge length of the unit cell then for zinc blende structure the distance of closest approach between cation and anion is (a) 2a (b) 3a (c) 2a (d) 3a 2 2 4 4 PASSAGE II Read the passage given below and answer the questions that follow: An element occurs in the body centred cubic lattice with cell edge of 300 pm. The density of the element is 8.0 g cm3 . 1. The number of atoms per unit cell is (a) 6 (b) 4 (c) 8 (d) 2 2. The coordination number of the element in the lattice is (a) 4 (b) 6 (c) 8 (d) 12 3. The number of nearest neighbours and the next nearest neighbours are respectively (a) 4 and 6 (b) 4 and 8 (c) 8 and 8 (d) 8 and 6 4. The distance of closest approach between the two atoms of the element in the lattice is (a) 260 pm (b) 300 pm (c) 600 pm (d) 150 pm 5. The atomic mass of the element is (a) 65 (b) 60 (c) 52 (d) 80 Answers Passage I 2. (b) 3. (a) 4. (c) 5. (d) 1. (c) 2. (c) 5. (a). 3. (d) 4. (a) Passage II 1. (d)

Unit 3: p-Block Elements  MULTIPLE CHOICE QUESTIONS  In each of the following questions only one option is correct. Select the correct option. 1. On addition of conc. H2SO4 to a CaC2O4, a reaction occurs. The correct reason is, (a) H2SO4 reduces CaC2O4 to CO2 (b) CaC2O4 changes to H2C2O4 (c) CaC2O4 gets oxidized to CO2 (d) H2SO4 is oxidized to SO3. 2. Salt X + Slaked lime  colourless gas that gives brown color with K2HgI4. The salt X could be, (a) Barium nitrate (b) Ammonium chloride (c) Copper sulphate (d) Calcium phosphate. 3. Which of the following pairs of ions are isoelectronic and iso-structural? (a) NO2+, NO3– (b) ClO3–, ICl4– (c) XeO32–, PCl3 (d) ClO3–, SO32–. 4. Halogens have a strong affinity for hydrogen. Which of the halogen acids should have highest bond dissociation enthalpy? (a) HF (b) HCl (c) HBr (d) HI. 5. AredsuucbesstaanccideifgieivdeKs MoffnOO42. when heated, turns an acidified Kl solution brown and The substance is: (a) hydrogen peroxide (b) potassium nitrate (c) potassium chlorate (d) ammonium nitrite. 6. There is no S—S bond in: (a) S2O42– (b) S2O52– (c) S2O32– (d) S2O7–. 7. SO2 differs from CO2 in that it: (b) dissolves in water to form an acid (a) does not turn limewater milky (d) supports in burning of Mg. (c) combines with O2 8. Pick out the incorrect statement regarding H2SO4 (a) When treated with H2SO4, HCOOH forms CO and H2O (b) Glucose, when treated with conc. H2SO4 forms carbon. (c) Conc. H2SO4 can’t oxidize HBr and HI to form Br2 and I2 respectively (d) Conc. H2SO4 reacts with NaNO3 or Na2SO3. 9. Strong heating of which of the following will not produce NO2 gas? (a) Pb(NO3)2 (b) Ba(NO3)2 (c) KNO3 (d) Hg(NO3)2. 10. Which of the following reagent does not give O2 gas on reaction with ozone? (a) K2MnO4 (b) SnCl2/HCl (c) FeSO4/H2SO4 (d) PbS. 29

30 Chemistry—XII 11. Which of the following is used as drying agent for ammonia gas? (a) Conc. H2SO4 (b) P2O5 (c) CaO (d) CaCl2. 12. The catalyst used in Haber’s process for manufacture of ammonia is (a) Fe/Mo (b) P2O5 (c) Pt (d) NiO. 13. Which of the following substance give dinitrogen on heating? (a) HNO3 (b) (NH4)2 Cr2O7 (c) NH4Cl (d) All of them. 14. Aqua regia is a mixture of (a) conc. HNO3 and conc. H2SO4 (b) conc. HCl and conc. H2SO4 in the ratio of 3 : 1 (c) conc. HCl and conc. HNO3 in the ratio of 3 : 1 (d) none of these. 15. When acidified solution of KMnO4 is dropped over sodium peroxide, the colourless gas produced is (a) dinitrogen (b) dioxygen (c) dihydrogen (d) hydrogen peroxide. 16. Which of following oxide is coloured as well as gas at room temperature? (a) Barium oxide (b) Sulphur dioxide (c) Nitrogen(IV) oxide (d) Nitrogen(II) oxide. 17. Which will quickly absorb oxygen gas? (a) Alkaline pyrogallol solution (b) Conc. H2SO4 (c) Lime water (d) Alkaline solution CuSO4. 18. Which of the following halides of phosphorus has least X–M–X bond angle? (a) PF3 (b) PCl3 (c) PB3 (d) PI3. 19. Which of the following on heating give O2 gas? (a) Lead nitrate (b) Potassium chlorate (c) Manganese dioxide (d) All the above. 20. Which of the following condition is not suitable for production of ammonia by Haber’s process? (a) High pressure (b) High temperature (c) Low temperature (d) Use of catalyst. 21. Tailing of mercury is due to formation of (a) Hg2O (b) HgO (c) Hg(OH)2 (d) HgCl2. (d) Au. 22. Ozone can be tested by (a) Ag (b) Hg (c) Zn 23. Ozone (b) turns blue litmus red (a) turns red litmus blue (d) is amphoteric to litmus. (c) is neutral to litmus 24. In which of the following O2 gas is collected? (a) Ethanol (b) Water (c) Mercury (d) Pyrogallol.

p-Block Elements 31 25. Halogens are all coloured (b) due to absorption of I.R. light (a) due to absorption of UV light (d) none of the above is correct. (c) due to absorption of visible light 26. Which of the following does not have S—S bond? (a) S2O42– (b) S2O32– (c) S2O52– (d) S2O72–. 27. Oxygen is more electronegative than sulphur, yet H2S is slightly acidic. This is because (a) water is highly associated compound (b) molecular mass of H2S > than that of H2O (c) H2S is gas under ordinary conditions while H2O is liquid (d) H—S bond is weaker than H—O bond. 28. The solubility of iodine in water increases by addition of (a) potassium iodide (b) chloroform (c) carbon disulphide (d) CCl4. 29. I2 reacts with concentrated HNO3 to form an oxo acid (a) HIO (b) HIO3 (c) HIO4 (d) HIO2. 30. The oxide which cannot be a reducing agent is (a) SO2 (b) NO2 (c) CO2 (d) ClO2. 31. Which form of sulphur is amorphous? (a) Rhombic sulphur (b) Plastic sulphur (c) Milk of sulphur (d) Monoclinic sulphur. 32. Dissolution of SO2 in water produces (a) H2SO4 (b) H2S2O7 (c) H2S2O8 (d) H2SO3. 33. The shape of ClO3– is (b) tetrahedral (a) triangular pyramid (d) triangular bipyramidal. (c) triangular planar 34. Which of the following halides is most acidic? (a) PCl3 (b) SbCl3 (c) BiCl3 (d) CCl4. (d) Al. 35. Inert pair effect is exhibit by (a) Pb (b) B (c) Si 36. The shape of XeF4 is (b) octahedral (c) planar (d) none of these. (a) tetrahedral 37. The range of oxidation states shown by phosphorus is from (a) – 3 to 0 (b) 0 to + 5 (c) – 3 to + 5 (d) 2 to + 4. 38. Which one of the following statements regarding helium is incorrect? (a) It is used to fill gas balloons instead of hydrogen because it is lighter and non inflammable (b) It is used in gas-cooled nuclear reactors (c) It is used to produce and sustain powerful superconducting magnets (d) It is used as a cryogenic agent for carrying out experiments at low temperatures.

32 Chemistry—XII 39. Order of boiling point is (b) HF > HBr > HI > HCl (a) HF > HI > HBr > HCl (d) HCl > HI > HBr > HF. (c) HCl > HBr > HI > HF 40. SO2 + H2S  product. The final product is (a) H2O + S (b) H2SO4 (c) H2SO3 (d) H2S2O3. 41. The correct order of acidity of halogenic acids is (a) HF < HCl < HBr < HI (b) HI < HBr < HCl < HF (c) HI < HCl < HBr < HF (d) HF < HBr < HI < HCl. 42. The correct order of electron affinity is (a) Cl > F > Br > I (b) F > Cl > Br > I (c) F > Br > Cl > I (d) Cl > Br > F > I. 43. Which of the following hydrogen halides is most volatile? (a) HF (b) HCl (c) HBr (d) HI. 44. Which of the following orders is not in accordance with the property stated against it? (a) F2 > Cl2 > Br2 > I2: Bond dissociation energy (b) F2 > Cl2 > Br2 > I2: Oxidising power (c) HI > HBr > HCl > HF: Acidic property in water (d) F2 > Cl2 > Br2 > I2: Electronegativity. 45. The increasing order of the first ionisation enthalpies of the elements B, P, S and F (lowest first) is (a) F < S < P < B (b) P < S < B < F (c) B < P < S < F (d) B < S < P < F. In each of the following questions two or more options are correct. Select the correct options. 46. If chlorine gas is passed dry slaked lime, two changes are observed in the oxidation number of chlorine during the reaction. These are ______ and______. (a) 0 to +5 (b) 0 to +3 (c) 0 to –1 (d) 0 to +1 47. Which of the following options are not in accordance with the property mentioned against them? (a) F2 > Cl2 > Br2 > I2 ...... Oxidising power. (b) AsH3 < PH3 < NH3 ...... Stability of hydride. (c) IF > BrF > ClF > IF ...... Order of stability. (d) HI < HBr < HCl < HF ...... Hydrogen-halogen bond strength. 48. Which of the following statements are correct? (a) I3+ is a polyhalide cation. (b) The X—X bond is more reactive than X—X bond in interhalogen. (c) Fulminate ion (OCN)– is a pseudo halide ion. (d) Interhalogen compounds are good oxidizing agents.

p-Block Elements 33 49. Which of the following statements are correct for SO2 gas? (a) It acts as bleaching agent in moist conditions. (b) It is used as antichlor. (c) It turn acidified dichromate green due to its oxidizing nature. (d) It cannot be prepared by the reaction of dilute H2SO4with metal sulphide. 50. Which of the following orders are correct as per the properties mentioned against each? (a) As2O3 < SiO2 < P2O3 < SO2 ...... Acid strength. (b) AsH3 < PH3 < NH3 Enthalpy of ...... Vaporization. (c) S < O < Cl < F ...... More negative electron gain enthalpy. (d) H2O > H2S > H2Se > H2Te ...... Thermal stability. 51. Which of the following statements are correct? (a) S–S bond is present in H2S2O6. (b) In peroxomonosulphuric acid (H2SO5) sulphur is in +6 oxidation state. (c) Fluorine can form two types of oxides, OF2 and O2F2. (d) Perchloric acid is weaker than Chloric acid. 52. In which of the following reactions conc. H2SO4 is used as an oxidizing reagent? (a) CaF2 + H2SO4  CaSO4 + 2HF (b) 2HI + H2SO4  I2 + SO2 + 2H2O (c) Cu + 2H2SO4  CuSO4 + SO2 + 2H2O (d) NaCl + H2SO4  NaHSO4 + HCl 53. Which of the following statements are true? (a) Argon is used for respiration by deep sea divers. (b) Ionization enthalpy of molecular oxygen is very close to that of xenon. (c) Hydrolysis of XeF2 gives XeO3 and HF. (d) Xenon fluorides are crystalline solids. 54. Which of the given ions can disproportionate? (a) ClO– (b) ClO2– (c) ClO4– (d) IO4– (d) FeO only 55. Which among the following is a false statement? (a) SO3 is obtained by the catalytic oxidation of SO2 (b) SO3 has trigonal pyramidal geometry is gaseous state (c) SO3 in gaseous state has all S–O bonds equivalent (d) SO3 gas shows more solubility in water than in H2SO4 56. Ferrous sulphate on heating in air gives (a) Ferric sulphate (b) SO2 (c) SO3

34 Chemistry—XII 57. The structures of O3 and N3– are iso structural with (a) SO2 and XeF2, respectively (b) N2O and NO2, respectively (d) H2O and I3–, respectively (c) XeO2 and Cl2O, respectively 58. Which of the following are peroxoacids of sulphur? (a) H2SO5 (b) H2S2O7 (c) H2S2O8 (d) H2S2O6 59. Hot conc. H2SO4 acts as moderately strong oxidizing agent. It oxidizes both metals and nonmetals. Which of the following element are oxidized by conc.H2SO4 producing SO2 in the reaction? (a) Cu (b) Fe (c) C (d) Zn 60. Which of the following is not tetrahedral in shape? (a) ICl4– (b) POCl3 (c) SF4 (d) SO42– 61. Which of the following statements regarding the oxides of sulphur are correct? (a) Sulphur monoxide is a colourless liquid. (b) Thermal decomposition of Fe2(SO4)3 gives only SO3. (c) Both SO2 and SO3 are mild reducing agent. (d) SO3 at room temperature exist in three allotropic forms i.e.,,  and . 62. Which of the following is wrong regarding H2S? (a) In laboratory, it is prepared by the reaction of FeS with H2SO4. (b) It is a strong reducing gas at room temperature. (c) Moisture impurity can be removed by drying with CaO. (d) When passed through acidic solution of KMnO4, violet colour solution is formed. Answers 1. (c) 2. (b) 3. (d) 4. (b) 5. (a) 6. (d) 7. (c) 8. (c) 11. (c) 12. (a) 13. (b) 14. (c) 9. (c) 10. (b) 17. (a) 18. (a) 19. (d) 20. (b) 23. (c) 24. (b) 25. (c) 26. (d) 15. (b) 16. (d) 29. (b) 30. (c) 31. (b) 32. (d) 35. (a) 36. (c) 37. (c) 38. (b) 21. (a) 22. (b) 41. (a) 42. (a) 43. (b) 44. (a) 47. (a), (d) 48. (a), (c), (d) 49. (a), (b) 50. (a), (d) 27. (d) 28. (a) 52. (b), (c) 53. (b), (c) 54. (a), (b) 55. (b), (d) 58. (a), (c) 59. (a), (c) 60. (a), (c) 61. (b), (d) 33. (b) 34. (c) 39. (a) 40. (a) 45. (d) 46. (c), (d) 51. (a), (b), (c) 56. (b), (c) 57. (a), (d) 62. (c), (d)

p-Block Elements 35  ASSERTION-REASON TYPE QUESTIONS  In each of the following questions two statements are given, one of the statement is labelled as Assertion A while the other one as Reason R. Examine the two statements carefully and mark the correct choice (a), (b), (c) or (d) according to the following instruction given below: (a) if both A and R are correct and R is correct explanation of A (b) if both A and R are correct but R is not correct the explanation of A (c) if A is correct but R is wrong (d) if A is wrong but R is correct. 1. Assertion A: Among chalcogens tendency of catenation is maximum for sulphur. Reason R: S—S bond is stronger than O—O bond. 2. Assertion A: The m.p./b.p. of noble gas are quite high. Reason R: The interparticle forces among noble gases in their liquid state are van der Waal forces. 3. Assertion A: Pink coloured solution of potassium permanganate turns green on passing O3 through it. Reason R: K2MnO4 is reduced by O3 to KMnO4. 4. Assertion A: NO3– ion and CO32– ions are isoelectronic. Reason R: Sodium is oxidised by H2 to sodium hydride. 5. Assertion A: White precipitate of silver chloride gets dissolved in NH4OH soln. Reason R: NH3 reacts with AgCl to form a soluble complex with formula [Ag(NH3)2]Cl. 6. Assertion A: Fresh strain of iodine can be removed by washing with hypo solution. Reason R: Hypo reduces iodine to colourless I– ions. 7. Assertion A: Sulphuric acid is more viscous than water. Reason R: In H2SO4 the S atom exhibit its highest oxidation state. 8. Assertion A: Conc. H2SO4 reacts with KCl to give Cl2 gas. Reason R: HCl cannot be oxidised by H2SO4. 9. Assertion A: Sulphur (IV) oxide can act as oxidising as well as reducing agent. Reason R: In sulphur (IV) oxide S assumes sp3 d hybrid state. 10. Assertion A: HBr is a stronger acid than HI. Reason R: Bond energy of HI is smaller than that of H—Br. 11. Assertion A: S8 molecule has puckered ring structure. Reason R: S8 molecule contains eight lone pairs. 12. Assertion A: Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Reason R: The reaction between nitrogen and oxygen requires high temperature. Answers 1. (a) 2. (d) 3. (c) 4. (b) 5. (a) 6. (a) 7. (b) 8. (d) 11. (c) 12. (a) 9. (c) 10. (d)

36 Chemistry—XII  MATCHING TYPE QUESTIONS  In the following questions match the items in Column I with the items in Column II. An item in Column I may match with more than one items in Column II. 1. Match the statements given in Column I and Column II Column I Column II (i) Square planar (a) POCl3 (ii) Linear (b) XeF4 (iii) Tetrahedral (c) ClO3– (iv) Pyramidal (d) I3– (e) XeOF4 2. Match the statements given in Column I and Column II Column I Column II (i) Caro’s acid (a) H2S2O3 (ii) Marshal’s acid (b) H2SO5 (iii) Pyrosulphuric acid (c) H2S2O8 (iv) Thiosulphuric acid (d) H2S2O7 (e) H4S2O6 1. (i)–(a); (ii)–(d); (iii)–(a); Answers 2. (i)–(b); (ii)–(c); (iii)–(d); (iv)–(c) (iv)–(a)  VERY SHORT ANSWER QUESTIONS  1. What is the hybrid state of S in SO42–? 2. Give one example each of normal oxide and mixed oxide. 3. What is tailing of mercury? How can it be removed? 4. Why silent electric discharge is used in the preparation of ozone? 5. Why black suspension of lead sulphide in water decolourises on passing ozone through it? 6. Tendency to show-2 oxidation state diminishes from sulphur to polonium in group 16. 7. Why group 17 elements are known as halogens? 8. Arrange the halogen acids in order of increasing acidic strength. 9. Which halogen has highest electronegativity and which has highest electron affinity?

p-Block Elements 37 10. How do boiling points vary among halogens on going down the group? 11. Mention two points illustrating the electropositive character of iodine. 12. Identify X in the following chemical reaction: Cl2 + 2X–  2Cl– + X2. 13. Give one example each of pseudo halide and pseudohalogen. 14. What does azote mean? 15. What is the hybrid state of Xe in XeF2, XeOF4 and XeO3 ? 16. Which compound led to the preparation of compounds of noble gases? 17. Write the balanced equation for complete hydrolysis of XeF6. 18. What is the shape of XeF4 molecule? 19. Complete the following equations: (i) XeF2 + H2O  (ii) XeF4 + O2F2  20. Which is the most stable thermodynamic form of phosphorus? 21. Write two uses of Selenium. 22. Which reaction from Bartlett to prepare first noble gas compound? 23. Arrange the noble gases in the order of increasing atomic size. 24. Why does oxygen not show an oxidation state of +4 and +6 like sulphur? 25. Which halogen does not have d-orbitals in its electronic configuration? 26. Which halogen does not form oxoacid in higher oxidation state? 27. On the basis of electronic configuration of halogen atoms indicate what valence states are characterized by F2, Cl2, Br2 and I2? 28. Which element in the periodic table has the highest ionization enthalpy? 29. Which halogen has the highest electron gain enthalpy? 30. Which oxides of nitrogen is solid? 31. Mention one use of P4O10. 32. Arrange the following halogens in the decreasing order of electron gain enthalpy: F, Cl, Br, I. 33. Which elements of zero group of the periodic table are expected to form compounds and why? 34. Covalent fluorides are more inert than other covalent halides? 35. Arrange the noble gases in the order of decreasing ionization enthalpies. 36. What kind of bond is expected between oxygen and fluorine in oxygen fluorides? 37. Which of following is more covalent : SbCl5 or SbCl3? 38. List some important minerals containing phosphorus. 39. Name two compounds in which oxygen has oxidation state different from –2. Answers 1. sp3 2. MgO, Fe3O4. 3. On passing ozone through mercury, it loses its meniscus due to formation of Hg2O. It is known as tailing of mercury. Hg2O, can be removed by washing Hg with water or dil. HCl.

38 Chemistry—XII 4. If silent electric discharge is not used the heat produced during sparking will decompose ozone. 5. Due to oxidation of PbS to PbSO4. 6. C12 H 22O11 H2SO4 12C  11H2O. sugar Black mass 7. Halogens means sea salt forming. 8. HF < HCl < HBr < HI. 9. F, Cl. 10. Increase down the group. 11. Lustre and existence of I+ and I3+. 12. Br, I 13. CN– and (CN)2. 14. It refers to nitrogen an old name which means without life. 15. sp3d; sp3d2; sp3. 16. PtF6 17. XeF6 + 3H2O  XeO3 + 6HF. 18. Square planar. 19. XeF6 + H2O  XeOF4 + 4HF 20. Black phosphorus. 21. Selenium is used : (i) in xerography, (ii) in photoelectric cells. 22. O2(g) + PtF6(g)  O2+[PtF6]–(s). 23. He < Ne < Ar < Kr < Xe < Rn. 24. Due to absence of d-orbital. 25. Fluorine. 26. Fluorine. 27. They characterize zero valence state. 28. Helium. 29. Chlorine. 30. N2O5. 31. P4O10 is used as a dehydrating agent because of its great affinity for water. 32. Cl > F > Br > I. The electron gain enthalpy decreases with increase in atomic size (except F). 33. Only higher members (Kr, Xe and Rn) are expected to form some compounds due to their low ionization enthalpies. 34. Fluorine forms stronger covalent bonds with other elements than does other halogens; because of its small size, high electronegativity. 35. He > Ne > Ar > Kr > Xe > Rn. The ionization enthalpy decreases in descending Group 18 due to increase in atomic size.

p-Block Elements 39 36. The bond expected is mainly covalent bond because electronegativity difference between oxygen and fluorine atoms is small. 37. pSobwCel5r ; because Sb5+ has smaller size, high charge density and greater polarizing than Sb3+. 38. (i) Hydroxyapatite : Ca5(PO4)3(OH) (ii) Fluorapatite, 3Ca3(PO4)2.CaF2 or Ca5(PO4)3F. 39. OF2, oxidation state of O = + 2 H2O2, oxidation state of O = – 1  FILL IN THE BLANKS  Fill in the following blanks with appropriate items: 1. Oxygen family constitutes elements of group ...... of periodic table. 2. SiO2 is ...... oxide. 3. Dioxygen is absorbed by alkaline solution of ...... . 4. Sodium dissolves in liquid ammonia to give ...... coloured solution. 5. Laughing gas is obtained by heating of ...... . 6. Ammonia and iodine react to give ...... . 7. Colourless gas produced by dropping KMnO4 over sodium peroxide is ...... . 8. ...... is anhydride of nitric acid. 9. Condensation of equimolar amounts of NO and NO2 will result in the formation of ...... . 10. I2 dissolves in KI(aq) to form ...... . 11. As the size of the cation ...... the basicity of the corresponding hydroxide increases. 12. The formula of laughing gas is ...... . 13. N(SiH3)3 has ...... geometry. 14. CN– is an example of ...... halide ion. 15. ...... is the first compound of noble gas prepared by ...... in 1962. 16. ........ acid gives ........ ion (Hypobromic, hypobromous, bromide, bromite, perbromate). 17. The tendency of atoms to undergo self-linking to form long chains or ring skeletons called ...... . 18. In the reaction; I2 + I–  I3–, the Lewis acid is ...... . 19. Among PCl3, CH3+, NH2– and NF3, ...... is least reactive towards water. 20. The angle P—P—P in P4 molecule is ...... degree ...... . 21. On heating RbICl2 will decompose to give ...... . 22. In contact process for the manufacture of H2SO4 the SO3 is absorbed in ...... . 23. The shape of CIF3 is ...... . 24. In chemical reaction of sugar and conc. H2SO4, the sulphuric acid acts as ...... . 25. In chemical reaction of copper and sulphuric acid, H2SO4 acts as ...... . 26. On commercial scale, fluorine is prepared by ...... . 27. On boiling sulphur with caustic soda solution ...... are produced.

40 Chemistry—XII 28. The two series of salts that sulphuric acid can produce are ...... and ...... . 29. The formal of rock phosphate is ...... . 30. Oxidation state of phosphorus in pyrophosphoric acid is ...... . 31. Oleum is ...... . 32. The number of molecules of hydration in borax is ...... . 33. The solubility of iodine in water is greatly increased by adding iodide ions because of formation of ...... . 34. The halogen which does not show variable oxidation state is ...... . 35. The formula of pyrophosphoric acid is ...... . 36. The chemical name and formula of hypo are respectively ...... . 37. The most volatile halogen acid is ...... . 38. The first compound of noble gases prepared by N. Bartlett was ...... . Answers 1. 16 2. Amphoteric 3. alkaline pyrogallol 4. Blue 5. Ammonium nitrate 6. NH3 . NI3 9. N2O3 7. O2 8. N2O5 12. N2O 10. KI3 11. increases 15. XePtF6 13. planar 14. pseudo 18. I2 21. Rb+ and ICl2– ions 16. Hypobromous, bromite 17. catenation 24. dehydrating agent 19. CH3+ 20. 60° 22. conc. H2SO4 23. T-shaped 25. acid as well as oxidising agent 26. electrolysis of 90% soln of KHF2 in HF 27. Na2S and Na2S2O3 28. sulphates and bisulphates 29. Ca3 (PO4)2 30. + 5 31. H2S2O7 32. (8) 33. I3– complexion 34. fluorine 35. H2P2O7 36. sodium thiosulphate 37. HCl 38. Xe+ [PtF6]–  TRUE/FALSE  State whether the following statements are true or false: 1. The oxidation state of fluorine is one and that of chlorine can be as high as seven. 2. The structure of XeF2 is square-planar. 3. The member of the oxygen family are also known as chalcogens. 4. The electronic configuration of halogens is ns2np2. 5. Ozone occurs naturally and cannot be prepared in the laboratory. 6. Ozone is much lighter than air. 7. Ozone acts as a mild bleaching agent and bleaches vegetable colouring water. 8. Ozone layer depletion can be checked by preventing the leakage of CFCs.

p-Block Elements 41 9. On an industrial scale, sulphur dioxide can be obtained by the action of concentrated sulphuric acid on copper turnings. 10. Sulphur dioxide molecule has a linear structure. 11. Sulphur dioxide is used as an anti-chlor, disinfectant and preservative. 12. Lead chamber process is the latest process used in the manufacture of sulphuric acid. 13. The catalyst used for the conversion of SO2 into SO3 in the contact process in V2O5. 14. Charring takes place when concentrated sulphuric acid is dropped on sugar. 15. Hydrochloric acid is obtained by passing hydrochloric acid gas in water. 16. H2S gas is liberated when dilute hydrochloric acid reacts with sodium sulphide. 17. H3PO is a dibasic acid. 18. Ammonia behaves as a Lewis acid. 19. Nitrogen differs markedly from the other members of its group. 20. The structyre of XeF2 is square planar. Answers 1. True 2. False 3. True 4. True 5. False 6. False 7. True 8. True 11. True 12. False 13. True 14. True 9. False 10. False 17. True 18. False 19. True 20. False 15. True 16. True  CASE STUDIES  PASSAGE I Read the passage given below and answer the questions that follow: Group 17 elements are known as halogens (sea-salt forming) their general electronic configuration is ns2. np5. Fluorine the first member of the group differs in several ways from the rest of the group. Halogens are highly reactive elements having strong affinity for hydrogen. All the halogen acids have low boiling points. 1. The oxidising power of halogen is correctly given in (a) F2 > I2 > Br2 > Cl2 (b) F2 > Cl2 > Br2 > I2 (c) I2 > Br2 > Cl2 > F2 (d) Cl2 > F2 > Br2 > I2. 2. The Gf° of HX (where X = F, Cl, Br, I) for the reaction, H2 + X2  2HX is (a) large and positive for all halogens (b) small and negative for all halogens (c) negative when X = F, Cl, Br and positive when X = I (d) Sometimes negative and some time positive. 3. At room temperature (298 K) which of the following is a liquid? (a) HF (b) HI (c) I2 (d) none of these.

42 Chemistry—XII 4. Solid Hydrofluoric acid is correctly represented by which of the following structures. F (a) ( H F H F )n (b) H HH F F F (d) HH H HH (c) F FF FF H 5. The strength of halogen acids follows the order (a) HF > HCl > HBr > HI (b) HI > HBr > HCl > HF (c) HCl > HF > HI > HBr (d) HF > HI > HBr > HCl 6. In the sequence of reactions given below, Y and Z are respectively, CF2Cl2 CCl4 X H2O 1 O2 + Y SiO2 Z 2 (a) F2 and SiF4 (b) HF and SiF4 (c) F2 and H2SiF6 (d) HF and H2SiF6. PASSAGE II Read the passage given below and answer the questions that follow: Noble gases are mert gases with a general configuration of ns2 . np6. These are monoatomic, colourless, odourless and tasteless. The first compound of noble gas Xe was obtained by reaction with PtF6. A large number of compounds of Xe with fluorine have been prepared. The structure of these compounds can be explained on the basis of VSEPR theory as well as the concept of hybridisation. 1. The formula of the compound of Xe and PtF6 is (d) Xe+ Pt F6–. (a) XeF6 (b) XeF4 (c) Xe2 Pt F6 (d) T-shaped. 2. The structure of XeO3 (c) pyramidal (a) linear (b) Planar 3. The shape and hybridization of some xenon oxyfluorides are given below. Which of these is incorrect. (a) XeOF2—T-shaped-sp3d (b) XeO2F2—Trigonal bipyramidal-sp3d (c) XeO3F2—Tetrahedral-sp3. (d) XeOF4—Square pyramidal-sp3d2 4. Which of the following is not formed by Xe? (a) XeF5 (b) XeF (c) XeF3 (d) All the three. 5. The number of lone pairs and bond pairs of electrons around Xe in XeOF4 respectively are (a) 0 and 5 (b) 1 and 5 (c) 1 and 4 (d) 2 and 3. 6. Which of the following statements is correct about the fluorides of xenon? (a) XePtF6 was the first noble gas compound isolated (b) with SbF5, XeF2 acts a Lewis base (c) With RbF, XeF6 acts as a Lewis acid (d) All are correct.

p-Block Elements 43 PASSAGE III Read the passage given below and answer the questions that follow: In spite of the predictions of stable noble gas compounds since at least 1902, unsuccessful attempts at their synthesis gave rise to the widely held opinion that noble gases are not only noble but also inert. It was not until 1962 that this dogma was shattered when Bartlett in Canada published the first stable wnoitbhleingaasshcoomrtptoimunedspXaenPmtFa6n. Tyhnieswdixsecnoovner, yratdriogng,earnedd a worldwide frenzy in this area, and krypton compounds were prepared and characterized. The recent discoveries show the ability of xenon to act as a ligand. The discovery by Seppelt’s group that more than one xenon atom can attach itself to a metal center which in the case of gold leads to surprisingly btoonadssi.nTghleeAbuon(IdIi)ncgeninte[rAiunXae4s]q2u+ ainrveoplvlaensa4rXaerrlaignagnedmseantttawcihthedabXyer-eAlautbivoenldy stable Au-Xe strong bonds length of about 274 pm. This discovery provides not only the first example of multiple xenon ligands but also represents the first strong metal-xenon bond. (Source: Christe, K.O. (2001). A renaissance in noble gas chemistry. Angewandte Chemie International Edition, 40(8), 1419-1421.) 1. In the complex ion [AuXe4]2+ , Xe acts as: (a) central atom (b) ligand (c) chelating agent (d) electrophile 2. Hybridisation shown by Au in [AuXe4]2+ is: (a) sp3 (b) sp3d (c) sp3d2 (d) sp2 3. Compounds of noble gases except .................. are known. (a) Krypton (b) Radon (c) Helium (d) Xenon 4. Xe is a ................. ligand. (b) bidantate (a) ambidentate (d) hexadentate (c) unidentate PASSAGE IV Read the passage given below and answer the questions that follow: In the last 10 years much has been learned about the molecular structure of elemental sulphur. lt is now known that many different types of rings are sufficiently metastable to exist at room temperature for several days. It is known that at high temperature, the equilibrium composition allows for a variety of rings and chains to exist in comparable concentration, and it is known that at the boiling point and above, the vapor as well as the liquid contains small species with three, four, and five atoms. The sulphur atom has the same number of valence electrons as oxygen. Thus, sulphur atoms S2 and S3 have physical and chemical properties analogous to those of oxygen and ozone. S2 has a ground state of 38 3s2*3s23pz23px2 = 3py2*3px1 = *3py1. S3, thiozone has a well-known uv spectrum, and has a bent structure, analogous to its isovalent molecules O3, SO2, and S2O. The chemistry of the two elements, sulphur and oxygen,

44 Chemistry—XII differs because sulphur has a pronounced tendency for catenation. The most frequently quoted explanation is based on the electron structure of the atom. Sulphur has low-lying unoccupied 3d orbitals, and it is widely believed that the 4s and 3d orbitals of sulfur participate in bonding in a manner similar to the participation of 2s and 2p orbitals in carbon. (Source: Meyer, B. (1976). Elemental sulfur. Chemical Reviews, 76(3), 367–388. doi:10.1021/cr60301a003) In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage. (a) Assertion and reason both are correct statements and reason is correct explanation for assertion. (b) Assertion and reason both are correct statements but reason is not correct explanation for assertion. (c) Assertion is correct statement but reason is wrong statement. (d) Assertion is wrong statement but reason is correct statement. 1. Assertion: Sulphur belongs to same group in the periodic table as oxygen. Reason: S2 has properties analogous to O2. 2. Assertion: Thiozone has bent structure like ozone. Reason: Ozone has a lone pair which makes the molecule bent. 3. Assertion: S2 is paramagnetic in nature. Reason: The electrons in *3px and *3py orbitals in S2 are unpaired. 4. Assertion: Sulphur has a greater tendency for catenation than oxygen. Reason: 3d and 4s orbitals of Sulphur have same energy. Answers Passage I 2. (c) 3. (a) 4. (c) 5. (b) 6. (d) 1. (b) 2. (c) 3. (c) 4. (d) 5. (b) 6. (d) 2. (b) 3. (c) 4. (c) Passage II 1. (d) Passage III 1. (a) Passage IV 2. (b) 3. (a) 4. (c) 1. (b)

Unit 6: Biomolecules  MULTIPLE CHOICE QUESTIONS  In each of the following questions only one option is correct. Select the correct option. 1. -D-Glucose and -D-Glucose are ________ . (a) Epimers (b) Anomers (c) Enantiomers (d) Structural isomers 2. Which of the following compounds is a non-reducing sugar? (a) Glucose (b) Fructose (c) Maltose (d) Sucrose 3. Nucleic acids are polymers of ________ . (a) Nucleosides (b) Nucleotides (c) Peptides (d) -Amino acids 4. Consider the structures of carbohydrates given below: CHO CH2OH H OH CO HO H HO H H OH H OH H OH H OH CH2OH CH2OH (+) rotation (–) rotation (A) (B) Which of the following statements is not correct? (a) A is aldohexose and B is ketohexose (b) A has D-configuration and B has L-configuration (c) A is dextrorotatory and B is laevorotatory (d) Both A and B can reduce Tollen’s reagent 5. Which of the following statements is not true about glucose? (a) It is an aldohexose (b) It exists in pyranose form (c) On heating with HI it forms 1-iodohexane (d) It is dextrorotatory 6. Structure of glycogen is similar to that of ________ . (a) Cellulose (b) Amylose (c) Amylopectin (d) Sucrose 75

76 Chemistry—XII 7. One molecule of sucrose, on hydrolysis, gives ______. (a) 2 molecules of fructose (b) 2 molecules of glucose (c) 1 molecule of glucose and 1 molecule of fructose (d) 1 molecule of glucose and 1 molecule of ribose 8. Which of the following reactions of glucose cannot be explained by its open chain structure? (a) Glucose is oxidized by Br2(aq) to gluconic acid (b) Glucose reacts with acetic anhydride to form pentaacetate derivative (c) Glucose does not react with 2,4-dinitrophenyl-hydrazine (2,4-DNP) (d) Glucose is reduced to n-hexane on reaction with hydrogen iodide 9. Which of the following B group vitamins can be stored in our body? (a) Vitamin B6 (b) Vitamin B12 (c) Vitamin B1 (d) Vitamin B2 10. Which of the following is vitamin C? (a) Citric acid (b) Aspartic acid (c) Adipic acid (d) Ascorbic acid 11. Which of the following structures represents a pair of anomers? H OH H OH HO H HO H H OH O H OH O HO H O H OH O HO H HO H H OH HO H H OH H OH HO H H OH HH HH CH2OH CH2OH CH2OH CH2OH I II III IV (a) I and II (b) I and III (c) I and IV (d) II and III 12. Which of the following polysaccharides is stored in the liver of animals? (a) Amylose (b) Cellulose (c) Amylopectin (d) Glycogen 13. In a protein amino acids are linked with each other in a specific sequence. This sequence of amino acids is known as the ________ . (a) primary structure of protein (b) secondary structure of protein (c) tertiary structure of protein. (d) quaternary structure of protein 14. Structure of a disaccharide formed by glucose and fructose is given below: 6CH2OH 5 O H 1 O H HH 1 HOH2C 4 25 HO OH H H OH O C6 H2OH 3 4 32 H OH OH H Identify anomeric carbon atoms in monosaccharide units (Here numbering of carbon atoms has been done arbitrarily).

Biomolecules 77 (a) C—1 of glucose and C—2 of fructose (b) C—1 of glucose and C—5 of fructose (c) C—4 of glucose and C—5 of fructose (d) C—5 of glucose and C—2 of fructose 15. Which of the following bases is not present in RNA? (a) Adenine (b) Uracil (c) Cytosine (d) Thymine 16. Structure of a disaccharide formed by condensation of two glucose units is given below: CH2OH CH2OH HH OH HH OH HO OH H O OH H OH H OH H OH Identify the incorrect statement about this disaccharide. (a) The two glucose molecules are linked through C—1 and C—4 (b) It represents a molecule of maltose (c) It is a non-reducing sugar (d) Its molecular formula is C12H22O11 17. Which of the following bases is not present in DNA? (a) Cytosine (b) Uracil (c) Adenine (d) Thymine 18. Nucleotide units in a nucleic acid are linked through ________ . (a) Glycoside linkage (b) Phosphodiester linkage (c) Peptide linkage (d) Heterocyclic bases 19. Which of the following statements is not correct? (a) In starch D-(+)-glucose units are linked by -glycoside linkage. (b) In cellulose D-(+)-glucose units are linked by -glycoside linkage (c) Lactose is a reducing sugar (d) In lactose two D-(+)-glucose units are linked through -glycoside linkage. In each of the following questions two or more options are correct. Select the correct options. 20. Which of the following are true about maltose? (a) It is a disaccharide. (b) It is a non-reducing sugar. (c) On hydrolysis, one molecule of maltose gives two molecules of glucose. (d) It has an -glycosidic linkage. 21. Which of the following are branched chain polymers of glucose? (a) Amylopectin (b) Glycogen (c) Cellulose (d) Amylose 22. Which of the following are reducing sugars? (a) Sucrose (b) Maltose (c) Lactose (d) Fructose

78 Chemistry—XII 23. Which of the following monosaccharides exist in furanose form? (a) Glucose (b) Fructose (c) Ribose (d) Galactose 24. Glucose and fructose are ________ . (a) Anomers (b) Hexoses (c) Isomers (d) Sugars 25. Which of the following amino acids are acidic? (a) H2N—CH—COOH (b) CH3—CH—COOH CH2—COOH NH2 (d) CH3—CH—CH2—CH—COOH (c) H2N—CH—(CH2)2—COOH COOH CH3 NH2 26. Lysine has the following structure: H2N—(CH2)4—CH—COOH It is a/an NH2 (a) -Amino acid (b) Basic -amino acid (c) Essential -amino acid (d) Dipeptide 27. Which of the following are fibrous proteins? (a) Albumin (b) Myosin (c) Keratin (d) Insulin 28. In fibrous proteins, polypeptide chains are held together by ________ . (a) Hydrogen bonds (b) Covalent bonds (c) Disulphide linkage (d) van der Waal’s forces 29. Which of the following are pyrimidine bases present in DNA? (a) Adenine (b) Thymine (c) Cytosine (d) Guanine 30. Which of the following heterocyclic bases are present in RNA as well as DNA? (a) Thymine (b) Uracil (c) Cytosine (d) Adenine 31. Which of the following vitamins are soluble in fats? (a) Vitamin D (b) Vitamin E (c) Vitamin C (d) Vitamin B6 Answers 1. (b) 2. (d) 3. (b) 4. (b) 5. (c) 6. (c) 11. (c) 12. (d) 7. (c) 8. (c) 9. (b) 10. (d) 17. (b) 18. (b) 23. (b), (c) 13. (a) 14. (a) 15. (d) 16. (c) 28. (a), (c) 19. (d) 20. (a), (c) 21. (a), (b) 22. (b), (c), (d) 24. (b), (c), (d) 25. (a), (c) 26. (a), (b), (c) 27. (b), (c) 29. (b), (c) 30. (c), (d) 31. (a), (b)

Biomolecules 79  ASSERTION-REASON TYPE QUESTIONS  In the following questions, two statements are given; one labeled as Assertion A and the other as Reason R. Examine the two statements carefully and mark the correct choice (a), (b), (c), (d) or (e) according to the instructions given below: (a) if both A and R are correct and R is correct explanation of A (b) if both A and R are correct but R is not correct explanation of A (c) if A is correct but R is wrong (d) if A is wrong but R is correct (e) if both A and R are wrong 1. Assertion A: All monosaccharides are sweet in taste. Reason R: All monosaccharides have the general formula C6H12O6. 2. Assertion A: In polysaccharides, monosaccharide units are linked by glycoside linkage. Reason R: Glycoside linkage is an ether linkage. 3. Assertion A: -Amino acids have zwitter ion structure. Reason R: -Amino acids have least conductivity at isoelectric point. 4. Assertion A: Fructose is the sweetest sugar. Reason R: Fructose is a functional isomer of glucose. 5. Assertion A: Starch on hydrolysis yields -D-glucose. Reason R: Starch is hydrolysed to glucose by the action of enzymes amylase and maltase. 6. Assertion A: Enzymes are proteins. Reason R: Enzymes are highly specific in nature. 7. Assertion A: Purine bases present in DNA are adenine and thymine. Reason R: The base uracil is present in DNA whereas the base thymine is present in RNA. 8. Assertion A: Thymine pairs with adenine whereas cytosine pairs with guanine in DNA molecule. Reason R: The hydrogen bonding between bases of two strands is highly specific. 9. Assertion A: Vitamin A can be stored in our body. Reason R: Vitamin A is fat soluble vitamin and all fat soluble vitamins can be stored in our body. 10. Assertion A: Maltose contains -glycosidic linkage. Reason R: Maltose is composed of two glucose units in which C–1 of one glucose unit is linked to C–4 of the second glucose unit. 11. Assertion A: Glycine is optically inactive. Reason R: Glycine is the simplest -amino acid. 12. Assertion A: Alanine is an essential -amino acid. Reason R: Alanine is 2-amino propanoic acid.

80 Chemistry—XII 1. (c) Answers 7. (e) 2. (b) 3. (b) 4. (b) 5. (b) 6. (b) 8. (a) 11. (b) 12. (d) 9. (a) 10. (a)  MATCHING TYPE QUESTIONS  In the following questions match the items in Column I with the items in Column II. An item in Column I may match with more than one items in Column II. 1. Match the items given in Column I with appropriate items in Column II. Column I Column II (i) Galactose (a) Reducing disaccharide (ii) Glycogen (b) Non-reducing disaccharide (iii) Maltose (c) Polysaccharide (iv) Sucrose (d) Monosaccharide 2. Match the vitamins given in Column I with the deficiency diseases listed in Column II. Column I Column II (i) Vitamin A (a) Osteomalacia (ii) Vitamin C (b) Beri beri (iii) Vitamin D (c) Scurvy (iv) Vitamin B1 (d) Xerophthalmia 3. Match the heterocyclic bases given in Column I with the appropriate items given in Column II. Column I Column II (i) Thymine (a) Purine base (ii) Adenine (b) A base present only in RNA (iii) Uracil (c) Pyrimidine base (iv) Guanine (d) A base present only in DNA

Biomolecules 81 4. Match the items given in Column I with the items given in Column II. Column I Column II (i) Peptide linkage (a) Deoxyribonucleic acid (ii) -Glycoside linkage (b) Proteins (iii) -Glycoside linkage (c) Cellulose (iv) Phosphodiester linkage (d) Amylose 5. Match the items in Column I with the names of carbohydrates in Column II. Column I Column II (a) Sucrose (i) A carbohydrate which yields only glucose on hydrolysis (b) Lactose (ii) A carbohydrate which yields glucose (c) Maltose and fructose on hydrolysis (d) Cellulose (iii) A carbohydrate which yields glucose (e) Amylose and galactose on hydrolysis (iv) A carbohydrate which reduces Tollen’s reagent Answers 1. (i)–(d); (ii)–(c); (iii)–(a); (iv)–(b) 2. (i)–(d); (ii)–(c); (iii)–(a); (iv)–(b) 3. (i)–(c), (d); (ii)–(a); (iii)–(b), (c); (iv)–(a) 4. (i)–(b); (ii)–(d); (iii)–(c); (iv)–(a) 5. (i)–(c), (d), (e); (ii)–(a); (iii)–(b); (iv)–(b), (c)  VERY SHORT ANSWER QUESTIONS  1. What are the hydrolysis products of lactose? 2. Name the two important functions of carbohydrates in the living bodies. 3. What do the following abbreviations represent: ala, val, leu, gly? 4. What is peptide bond? 5. What is invert sugar? 6. What is a nucleoside? 7. What is zwitter ion? Give zwitter ion structure of glycine and glycylalanine. 8. Name the linkage holding amino acids in a polypeptide. 9. Write the sequence of bases on mRNA molecule synthesised on the following strand of DNA, AGCGATTAC. 10. Define the term native state as applied to proteins. 11. Name the steroid hormone that regulates the male sex-organs. 12. To which category does hormone thyroxin belong?

82 Chemistry—XII 13. What is the cause of goitre? 14. Which hormones are used by athletes to increase their body weight and strength of muscles? 15. During change of milk into curd, what happens to the sugar present in it? 16. Why must vitamin C be supplied regularly in diet? 17. Amino acids may be classified as -, -, -, -, etc. depending upon the relative position of amino group with respect to carboxyl group. Which type of amino acids form polypeptide chains? 18. In human systems starch acts as nutrient but cellulose does not. Why? 19. Name the purines present in DNA. 20. How do you account for the fact that all the six carbon atoms in glucose molecule are in straight chain? 21. Except for vitamin B12, all other vitamins of group B, should be supplied regularly in diet. Why? 22. Name the two important secondary structures of proteins. 23. Name the vitamin which is essential for proper clotting of blood. 24. Write the full forms of DNA and RNA. 25. Write the structure of the product obtained when glucose is oxidised with nitric acid. Answers 1. D-Galactose and D-Glucose. 2. They act as constituents of cell membrane and also as biofuels. 3. alanine, valine, lucine, glycine. 4. The bond which links various amino acid units in peptides and proteins (—CO—NH—). 5. Equimolar mixture of -D-glucose and -D-fructose. It is formed by hydrolysis of sucrose. 6. Product formed by attachment of a nitrogenous base (purine or pyrimidine) to the sugar unit (ribose or deoxyribose) at C1 by -linkage. 7. N H3—CH2—COO–(glycine); CH 3 | N H CH CO NH CH CO – 3  2     O. (glycylalanine) 8. Peptide bond. 9. UCGCUAAUG. 10. A protein found in a living system with definite configuration and biological activity is called native protein. 11. Testosterone. 12. Amino acid. 13. Deficiency of iodine.

Biomolecules 83 14. Cortisone. 15. Milk sugar (lactose) changes into lactic acid. 16. Vitamin C, being a water soluble vitamin, is not stored in our body and hence it has to be supplied regularly in diet. 17. -amino acids. R—CH—COOH NH2 18. Human body does not contain enzymes which can cause hydrolysis of cellulose to glucose. Thus, cellulose cannot act as nutrient. 19. Adenine and guanine. 20. Glucose on reaction with HI gives n-hexane. 21. Vitamin B12 is fat soluble whereas others are water soluble. 22. -Helix structure and -Pleated sheet structure. 23. Vitamin K. 24. Deoxyribonucleic acid and ribonucleic acid. 25. Saccharic acid or Glucaric acid.  FILL IN THE BLANKS  Fill in the following blanks with appropriate items: 1. Insulin is secreted by ...... 2. The three parts of a nucleotide are: a phosphate group, a base and a ...... 3. The linkage holding monosaccharide units in maltose is ...... 4. Primary structure of proteins refers to ...... 5. The sugar in RNA is ...... 6. The helical structure of proteins is stabilised by ...... 7. The three dimensional structure of DNA was proposed by ...... 8. The chemical changes in DNA molecule that could lead to synthesis of proteins with an altered amino acid sequence is called ...... 9. ...... is a monosaccharide which is sweeter than sucrose. 10. The chemical name of vitamin C is ...... Answers 1. pancreas 2. a sugar 3. glycoside linkage 4. sequence of -amino acids 5. D-ribose 6. H-bonds 7. James Watson and Francis Crick 8. mutation 9. fructose 10. ascorbic acid

84 Chemistry—XII  TRUE/FALSE  State whether the following statements are true or false: 1. DNA contains the base uracil. 2. Fibroin is a globular protein. 3. Glycogen on hydrolysis gives sucrose. 4. RNA has a single brand. 5. Most of the naturally occurring carbohydrates belong to the D-series. 6. Starch cannot be hydrolysed in human digestive system. 7. The disease sickle cell anaemia is due to defected haemoglobin. 8. Haemoglobin is a conjugated protein. 9. The genetic information in DNA is stored in the form of sequence of bases. 10. Valine is an essential amino acid. 11. Insulin is secreted by pancreas. 12. The synthesis of proteins is carried out by RNA’s. Answers 1. False 2. False 3. False 4. True 5. True 6. False 7. True 8. True 11. True 12. True 9. True 10. True  CASE STUDIES  PASSAGE I Read the passage given below and answer the questions that follow: Disaccharides on hydrolysis yield two molecules of monosaccharides per molecule. All monosaccharides are reducing sugars whereas all disaccharides are not reducing sugars. A monosaccharide containing aldehyde group is called aldose whereas the one containing keto group is called ketose. 1. Which of the following will not give silver mirror test? (a) Maltose (b) Glucose (c) Fructose (d) Sucrose. 2. Which of the following is a ketose? (a) Erythrose (b) Ribose (c) Glucose (d) Fructose. 3. The hydrolysis products of lactose are (b) Glucose + Galactose (a) Glucose + Fructose (d) Galactose + Mannose. (c) Galactose + Fructose PASSAGE II Read the passage given below and answer the questions that follow: Adenosine triphosphate (ATP) is the energy-carrying molecule found in the cells of all living things. ATP captures chemical energy obtained from the breakdown of food molecules and releases it to fuel other cellular processes. ATP is a nucleotide that consists of three main structures: the nitrogenous base, adenine; the sugar, ribose; and a chain of three

Biomolecules 85 phosphate groups bound to ribose. The phosphate tail of ATP is the actual power source which the cell taps. Available energy is contained in the bonds between the phosphates and is released when they are broken, which occurs through the addition of a water molecule (a process called hydrolysis). Usually only the outer phosphate is removed from ATP to yield energy; when this occurs ATP is converted to adenosine diphosphate (ADP), the form of the nucleotide having only two phosphates. The importance of ATP (adenosine triphosphate) as the main source of chemical energy in living matter and its involvement in cellular processes has long been recognized. The primary mechanism whereby higher organisms, including humans, generate ATP is through mitochondrial oxidative phosphorylation. For the majority of organs, the main metabolic fuel is glucose, which in the presence of oxygen undergoes complete combustion to CO2 and H2O: C6H12O6 + 6O2  6O2 + 6H2O + energy The free energy (G) liberated in this exergonic (G is negative) reaction is partially trapped as ATP in two consecutive processes: glycolysis (cytosol) and oxidative phosphorylation (mitochondria). The first produces 2 mol of ATP per mol of glucose, and the second 36 mol of ATP per mol of glucose. Thus, oxidative phosphorylation yields 17-18 times as much useful energy in the form of ATP as can be obtained from the same amount of glucose by glycolysis alone. The efficiency of glucose metabolism is the ratio of amount of energy produced when 1 mol of glucose oxidised in cell to the enthalpy of combustion of glucose. The energy lost in the process is in the form of heat. This heat is responsible for keeping us warm. (Source: Ereciriska, M., & Silver, I. A. (1989). ATP and Brain Function. Journal of Cerebral Blood Flow & Metabolism, 9(1), 2-19. https://doi.org/10.1038/jcbfm.1989.2 and https:// www.britannica.com/science/adenosine-triphosphate) 1. Cellular oxidation of glucose is a: (a) spontaneous and endothermic process (b) non spontaneous and exothermic process (c) non spontaneous and endothermic process (d) spontaneous and exothermic process 2. What is the efficiency of glucose metabolism if 1 mole of glucose gives 38ATP energy? (Given: The enthalpy of combustion of glucose is 686 kcal, 1 ATP = 7.3 kcal) (a) 100% (b) 38% (c) 62% (d) 80% 3. Which of the following statement is true? (a) ATP is a nucleoside made up of nitrogenous base adenine and ribose sugar . (b) ATP consists the nitrogenous base, adenine and the sugar, deoxyribose. (c) ATP is a nucleotide which contains a chain of three phosphate groups bound to ribose sugar. (d) The nitrogenous base of ATP is the actual power source. 4. Nearly 95% of the energy released during cellular respiration is due to: (a) glycolysis occurring in cytosol (b) oxidative phosphorylation occurring in cytosol (c) glycolysis in occurring mitochondria (d) oxidative phosphorylation occurring in mitochondria

86 Chemistry—XII 5. Which of the following statements is correct: (a) ATP is a nucleotide which has three phosphate groups while ADP is a nucleoside which three phosphate groups. (b) ADP contains a nitrogenous bases adenine, ribose sugar and two phosphate groups bound to ribose. (c) ADP is the main source of chemical energy in living matter. (d) ATP and ADP are nucleosides which differ in number of phosphate groups. PASSAGE III Read the passage given below and answer the questions that follow: EVIDENCE FOR THE FIBROUS NATURE OF DNA The basic chemical formula of DNA is now well established. As shown in Figure 1 it consists of a very long chain, the backbone of which is made up of alternate sugar and phosphate groups, joined together in regular 3 5 phosphate di-ester linkages. To each sugar is attached a nitrogenous base, only four different kinds of which are commonly found in DNA. Two of these—adenine and guanine— are purines, and the other two thymine and cytosine-are pyrimidines. A fifth base, 5-methyl cytosine, occurs in smaller amounts in certain organisms, and a sixth, 5-hydroxy-methyl- cytosine, is found instead of cytosine in the T even phages. It should be noted that the chain is unbranched, a consequence of the regular internucleotide linkage. On the other hand the sequence of the different nucleotides is, as far as can be ascertained, completely irregular. Thus, DNA has some features which are regular, and some which are irregular. A similar conception of the DNA molecule as a long thin fiber is obtained from physicochemical analysis involving sedimentation, diffusion, light scattering, and viscosity measurements. These techniques indicate that DNA is a very asymmetrical structure approximately 20 A wide and many thousands of angstroms long. Estimates of its molecular weight currently center between 5 × 106 and 107 (approximately 3 × 104 nucleotides). Surprisingly each of these measurements tend to suggest that the DNA is relatively rigid, a puzzling finding in view of the large number of single bonds (5 per nucleotide) in the phosphate-sugar back bone. Recently these indirect inferences have been confirmed by electron microscopy. (Source: Watson, J. D., & Crick, F. H. (1953, January). The structure of DNA. In Cold Spring Harbor symposia on quantitative biology (Vol. 18, pp. 123-131). Cold Spring Harbor Laboratory Press.) 1. Purines present in DNA are: (b) guanine and thymine (a) adenine and thymine (c) cytosine and thymine (d) adenine and guanine 2. DNA molecule has .................. internucleotide linkage and .................. sequence of the different nucleotides (a) regular, regular (b) regular, irregular (c) irregular, regular (d) irregular, irregular

Biomolecules 87 3. DNA has a ................. backbone (a) phosphate-purine (b) pyrimidines-sugar (c) phosphate-sugar (d) purine-pyrimidine 4. Out of the four different kinds of nitrogenous bases which are commonly found in DNA, ................. has been replaced in some organisms. (a) adenine (b) guanine (c) cytosine (d) thymine PASSAGE IV Read the passage given below and answer the questions that follow: Polysaccharides may be very large molecules. Starch, glycogen, cellulose, and chitin are examples of polysaccharides. Starch is the stored form of sugars in plants and is made up of amylose and amylopectin (both polymers of glucose). Amylose is soluble in water and can be hydrolyzed into glucose units breaking glycocidic bonds, by the enzymes -amylase and -amylase. It is straight chain polymer. Amylopectin is a branched chain polymer of several D-glucose molecules. 80% of amylopectin is present in starch. Plants are able to synthesize glucose, and the excess glucose is stored as starch in different plant parts, including roots and seeds. The starch that is consumed by animals is broken down into smaller molecules, such as glucose. The cells can then absorb the glucose. Glycogen is the storage form of glucose in humans and other vertebrates, and is made up of monomers of glucose. It is structurally quite similar to amylopectin. Glycogen is the animal equivalent of starch. It is stored in liver and skeletal muscles. Cellulose is one of the most abundant natural biopolymers. The cell walls of plants are mostly made of cellulose, which provides structural support to the cell. Wood and paper are mostly cellulosic in nature. Like amylose, cellulose is a linear polymer of glucose. Cellulose is made up of glucose monomers that are linked by bonds between particular carbon atoms in the glucose molecule. Every other glucose monomer in cellulose is flipped over and packed tightly as extended long chains. This gives cellulose its rigidity and high tensile strength—which is so important to plant cells. Cellulose passing through our digestive system is called dietary fiber. (Source: https://chem.libretexts.org) 1. In animals, Glycogen is stored in: (b) Spleen (a) Liver (c) Lungs (d) Small Intestine 2. Amylose is: (a) straight chain, water insoluble component of starch ,which constitutes 20% of it. (b) straight chain, water soluble component of starch ,which constitutes 20% of it. (c) branched chain, water insoluble component of starch,which constitutes 80% of it. (d) branched chain, water soluble component of starch, which constitutes 80% of it. 3. Which biopolymer breaks down to release glucose, whenever glucose levels drop in Our body: (a) starch (b) cellulose (c) chitin (d) glycogen 4. The linkages which join monosaccharides to form long chain polysaccharides: (a) Peptide linkage (b) Disulphide bonds (c) Hydrogen bonds (d) Glycosidic linkage