NBSE Question Papers Chemistry Term-1 (Set-3) for Class 12

Class 12  SET-3 Series NBSE/XII/2021 TERM-I Code No. 043/12/3 Roll No.  Candidates must write the Code No. on the title page of the OMR sheet. l Please check that this question paper contains 8 pages. l Code number given on the right hand side of the question paper should be written on the title page of the OMR sheet. l Please check that this question paper contains 55 questions. l 15 minutes time has been allotted to read this question paper. CHEMISTRY Time Allowed : 90 Minutes Maximum Marks : 35 General Instructions: 1. The Question Paper contains three sections. 2. Section A has 25 questions. Attempt any 20 questions. 3. Section B has 24 questions. Attempt any 20 questions. 4. Section C has 6 questions. Attempt any 5 questions. 5. All questions carry equal marks. 6. There is no negative marking. NBSE 2021 1 [P.T.O.

SECTION-A This section consists of 25 multiple choice questions with overall choice to attempt any 20 questions. In case more than desirable number of questions are attempted, ONLY first 20 will be considered for evaluation. 1. A metallic crystal has the bcc type packing pattern. What percentage of volume of this lattice is empty space? (a) 68% (b) 32% (c) 26% (d) 74% 2. The correct order of electron affinity of the given elements is (a) O > S > Se > Te > Po (b) S > O > Se > Te > Po (c) S > Se > Te > Po > O (d) Po > Te > Se > S > O 3. The boiling point of a solution containing a non-volatile solute is (a) depressed (b) elevated (c) remains unchanged (d) none of these 4. In Friedel-Crafts alkylation besides AlCl3 other reactants are (a) C6H6 + NH3 (b) C6H6 + CH4 (c) C6H6 + CH3Cl (d) C6H6 + CH3COCl 5. Which of the following reaction confirms the presence of carbonyl group ( C O) in glucose? (a) Reaction with HI (b) Reaction with hydroxylamine (c) Reaction with HCN (d) Both (b) and (c) 6. The total number of tetrahedral voids in the face centred unit cell is (a) 6 (b) 8 (c) 10 (d) 12 7. Aspirin is an acetylation product of (a) p-dihydroxybenzene (b) o-hydroxybenzoic acid (c) o-dihydroxybenzene (d) m-hydroxybenzoic acid 8. Which of the following statements is incorrect? (a) Among halogens, radius ratio between iodine and fluorine is maximum. (b) Leaving F—F bond, all halogens have weaker X—X bond than X—X′ bond in interhalogens. (c) Among interhalogen compounds maximum number of atoms are present in iodine fluoride. (d) Interhalogen compounds are more reactive than halogen compounds. 9. A compound formed by elements X and Y crystallises in a cubic structure in which the X atoms are at the corners of a cube and the Y atoms are at the face centres. The formula of the compound is (a) XY3 (b) X3Y (c) XY (d) XY2 10. The reaction between phenol, chloroform and aq. alkali solution is called as (a) Claisen reaction (b) Wurtz reaction (c) Reimer Tiemann reaction (d) Cannizzaro’s reaction 11. The factor ∆Tb/Kb represents (a) molality (b) normality (c) formality (d) molarity NBSE 2021 2

12. The reagents for the following conversion is/are Br ? H H Br (a) Zn/CH3OH (b) alcoholic KOH followed by NaNH2 (c) aqueous KOH followed by NaNH2 (d) alcoholic KOH 13. The ionization constant of phenol is higher than the ethanol because (a) phenoxide ion is stronger base than ethoxide ion (b) phenoxide ion is stabilized through delocalization. (c) phenoxide ion is less stable than ethoxide ion (d) phenoxide ion is bulkier than ethoxide ion 14. Oxygen does not show –2 oxidation state in the case of (a) OH2 (b) CO2 (c) OF2 (d) OCl2 15. Which of the following naturally occurring a-amino acids is optically inactive? (a) Glycine (b) Alanine (c) Leucine (d) Valine 16. C3H8 + Cl2 light→ C3H7Cl + HCl is an example of (a) substitution (b) elimination (c) addition (d) rearrangement reaction 17. CH3CH2CH2Cl alc. KOH→ B HBr→ C Na/ether→ D (a) Propane (b) 2, 3-Dimethylbutane (c) Hexane (d) Allyl bromide 18. Bleaching powder is formed by the interaction of Cl2 and (a) a dilute solution of Ca(OH)2 (b) a concentrated solution of Ca(OH)2 (c) dry calcium oxide (d) dry slaked lime 19. 50 mL of aqueous solution of glucose C6H12O6 (Molar mass:180 g/mol) contains 6.02 × 1022 molecules. The concentration of the solution will be (a) 0.1 M (b) 0.2 M (c) 1.0 M (d) 2.0 M 20. In quantitative analysis when H2S is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. HNO3, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives (a) deep blue precipitate of Cu(OH)2 (b) deep blue solution of [Cu(NH3)4]2+ (c) deep blue solution of Cu(NO3)2 (d) deep blue solution of Cu(OH)2.Cu(NO3)2 21. XeF6 on complete hydrolysis gives (a) Xe (b) XeOF2 (c) XeO2 (d) XeO3 22. Partial pressure of a solution component is directly proportional to its mole fraction. This statement is known as (a) Henry’s law (b) Raoult’s law (c) Distribution law (d) Ostwald’s dilution law NBSE 2021 3 [P.T.O.

23. Which of the following is an example of aldohexose? (a) Sucrose (b) Glucose (c) Fructose (d) Lactose 24. Which of the following bonds has the highest energy? (a) Se—Se (b) Te—Te (c) S—S (d) O—O 25. Phenol is less acidic than (a) ethanol (b) o-nitrophenol (c) o-methylphenol (d) o-methoxyphenol SECTION-B This section consists of 24 multiple choice questions with overall choice to attempt any 20 questions. In case more than desirable number of questions are attempted, ONLY first 20 will be considered for evaluation. 26. If RBC is placed in 0.91% NaCl solution then it will (a) shrink (b) swell (c) neither shrink nor swell (d) either shrink or swell 27. Which of the following is halogen exchange reaction? A. RX + NaI → RI + NaX B. C C + HX —® C C C. R — OH + HX ZnCl2 → R — X + H2O HX CH CH CH 3 3 3 +X D. 2 Fe + dark XX (a) A (b) B (c) C (d) D 28. The vapour pressure of water at room temperature is 23.8 mm Hg. What will be the vapour pressure of an aqueous solution of sucrose with mole fraction equal to 0.12? (a) 2.86 mm Hg (b) 5.12 mm Hg (c) 15.31 mm Hg (d) 20.94 mm Hg 29. Which of the following element has highest electronegativity? (a) Br (b) Cl (c) F (d) I 30. Total volume of atoms present in a face centred cubic unit cell of a metal is (r is atomic radius) (a) 20 πr 3 (b) 24 πr3 (c) 12 πr 3 (d) 16 πr 3 3 3 3 3 31. Which of the following is known as Sandmeyer reaction? (a) C6H6 + CH3Cl AlCl3→ C6H5CH3 (b) C6H5OH CO2, NaOH→ C6H5(OH) COOH (c) C6H5N2+ Cl– Cu2Cl2→ C6H5Cl + N2↑ (d) 2HCHO → CH3OH + HCOONa NBSE 2021 4

32. Mark the wrong statement about denaturation of proteins. (a) The primary structure of the protein does not change. (b) Globular proteins are converted into fibrous proteins. (c) Fibrous proteins are converted into globular proteins. (d) The biological activity of the protein is destroyed. 33. The product formed when hot NaOH reacts with Cl2 is (a) NaOCl (b) NaClO3 (c) NaClO4 (d) NaClO2 34. At room temperature, HCl is a gas while HF is a liquid. This is because (a) H—F bond is covalent (b) H—F bond is ionic (c) H—F has metallic bond (d) H—F has hydrogen bond 35. If liquids A and B forms an ideal solution, the (a) enthalpy of mixing is zero (b) entropy of mixing is zero (c) free energy of mixing is zero (d) free energy as well as entropy of mixing is zero. 36. Which of the following compounds will be most readily attacked by an electrophile? (a) Chlorobenzene (b) Benzene (c) Phenol (d) Toluene 37. When NaCl crystal is doped with MgCl2, the nature of defect produced is (a) Interstitial (b) Schottky (c) Frenkel (d) Impurity 38. Chlorine is used in (a) manufacture of nitrocellulose products (b) extracting glue from bones (c) extraction of gold and platinum (d) enrichment of U–235 39. In 1962, Neil Bartlett prepared a red coloured compound which is formulated as (a) O2+PtF4– (b) O2+PtF6– (c) O2+PtF5– (d) PtF6– 40. Which of the following alcohols will yield the corresponding alkyl chloride on reaction with concentrated HCl at room temperature? (a) Propan-1-ol (b) Butan-2-ol (c) 2-Methylbutan-1-ol (d) 2-Methylbutan-2-ol 41. 1-Propanol and 2-propanol can be distinguished by (a) oxidation with KMnO4 followed by reaction with Fehling solution. (b) oxidation with K2Cr2O7 (acidic) followed by reaction with Fehling solution. (c) oxidation by heating with Cu followed by reaction with Fehling solution. (d) oxidation with conc. H2SO4 followed by reaction with Fehling solution. 42. C7H8 3C∆l2→A Br2 /Fe→ B Zn/HCl→ C The compound C is (b) m-bromotoluene (a) o-bromotoluene (d) 3-bromo-2,4,6-trichlorotoluene (c) p-bromotoluene NBSE 2021 5 [P.T.O.

43. In the halogen family, the oxidising action increases in the order (a) F2 < Cl2 < Br2 < I2 (b) Cl2 < I2 < Br2 < F2 (c) I2 < F2 < Cl2 < Br2 (d) I2 < Br2 < Cl2 < F2 44. Number of atoms in one molecule of rhombic sulphur is (a) 3 (b) 4 (c) 8 (d) Infinite 45. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): A solution of n-hexane and n-heptane is an ideal solution. Reason (R): The intermolecular attractive forces between the solvent-solvent and solute-solute are nearly equal to those between solute-solvent. (a) Both A and R are true and R is the correct explanation A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. 46. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): 2-Butene on reductive ozonolysis gives acetaldehyde. Reason(R): Acetaldehyde on reduction with strong reducing agent like LiAlH4 reduces to ethanol. (a) Both A and R are true and R is the correct explanation A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. 47. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A) : Sulphur belongs to same period in the periodic table as oxygen. Reason (R): S2 has properties analogous to O2 (a) Both A and R are true and R is the correct explanation A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. 48. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): Boiling points of alkyl halides decrease in the order    R—I > R — Br > R—Cl > R—F Reason (R): van der Waals forces decrease with increase in the size of halogen atom. (a) Both A and R are true and R is the correct explanation A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. 49. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): Thiozone (S3) has bent structure like ozone. Reason (R): Ozone has a lone pair on central oxygen atom which makes the molecule bent. NBSE 2021 6

(a) Both A and R are true and R is the correct explanation A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true. SECTION-C This section consists of 6 multiple choice questions with an overall choice to attempt any5. In case more than desirable number of questions are attempted, ONLY first 5 will be considered for evaluation. 50. Match the following Column I Column II (i) Fibrous proteins A. Five membered ring (ii) Globular proteins B. Dipolar ion exists as neutral ( iii) Isoelectric point C. Soluble in water (iv) Furanose D. Insoluble in water (a) (i)-D, (ii)-C, (iii)-B, (iv)-A (b) (i)-B, (ii)-C, (iii)-D, (iv)-A (c) (i)-B, (ii)-A, (iii)-D, (iv)-C (d) (i)-C, (ii)-D, (iii)-B, (iv)-A 51. Which of the following analogies is correct? (a) Phenol with Br2 in CS2 : Monosubstituted product : : Phenol with bromine water: Trisubstituted product NH OH 2 OH (b) Anisole : : : o-Cresol : OH NO 2 (c) Phenol with dil.HNO3 : NO 2 : : Phenol with conc. HNO3 : (Major Product) (d) Butan-1-ol on heating with HBr : 1-Bromobutane is formed :: 2-Methylbutan-2-ol on heating with HBr : 2-Methylbut-2-ene is formed 52. Complete the following analogy. Molality : A : : Molarity : B (a) A : Not preferred for mass determination of polymers B : Preferred for mass determination of polymers (b) A : Number of moles dissolved per kg of solvent, B : Number of moles dissolved per litre of solvent, NBSE 2021 7 [P.T.O.

(c) A: Independent of temperature, B : Dependent on temperature (d) A : Depends on pressure, B : Independent of pressure Case I: Read the passage given below and answer the following questions 53-55 Crystalline solids have been known and appreciated since antiquity, in particular single crystal jewels. The elements of symmetry in single crystals of minerals were considered in modern times by R. J. Haüy in 1798. Soon after, the theoretical publications of W. H. Miller on hkl notation (1839), A. Bravais on 14 lattices (1845), A. Schönflies (1892) and W. Barlow (1898) on 230 space groups, with innumerable contributions from others, resulted in the modern theory of geometrical crystallography. Theory of crystallography describes ideal crystal structures. The atomic arrangements of real materials depart in many ways from the ideal, hence the theories of crystal defects and disorder. The discovery by René-Just Haüy that a macroscopic crystal is made up of minuscule sized crystals all of the same shape, is the basis of crystallography. On extrapolation of this concept to the atomic level, the position of every atom in the perfect structure of any crystal can be predicted using the formula well-known to crystallographers:        ratom = M(r0 , atom) + u . a + v . b + w . c Application of this formula with a given atomic motif creates a perfect crystal structure, usually represented by packing of spheres. Considering now amorphous solids, it is conjectured that the positions of atoms cannot be predicted by any form of equation, which implies translational symmetry. Instead, it is hypothesised that in a perfect amorphous solid any straight line of arbitrarily direction that passes through it will be divided by its spheres/atoms into irregular intervals of random sequence, which can be represented by a corresponding statistical distribution function. (Source: Zbigniew H. Stachurski. On Structure and Properties of Amorphous Materials. Materials (Basel). 2011 Sep; 4(9): 1564–1598) 53. Solid A is very hard, electrical insulator in solid as well as molten state and melts at extremely high temperature. What type of solid is it? (a) Ionic (b) Molecular (c) Covalent (d) Metallic 54. Which of the following is a crystalline solid? (a) Glass (b) Sodium chloride (c) Rubber (d) Plastic 55. Which of the following is true about the value of refractive index of quartz glass? (a) Same in all direction (b) Different in different directions (c) Can not be measured (d) Always zero NBSE 2021 8