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

Class 12  SET-1 Series NBSE/XII/2021 TERM-I Code No. 043/12/1 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. 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 2. 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% 3. The mixture that forms minimum boiling azeotrope is (a) methanol – formic acid (b) chloroform – acetone (c) water – nitric acid (d) n-hexane-acetone 4. The total number of tetrahedral voids in the face centred unit cell is (a) 6 (b) 8 (c) 10 (d) 12 5. In Friedel-Crafts alkylation besides AlCl3 other reactants are (a) C6H6 + NH3 (b) C6H6 + CH4 (c) C6H6 + CH3Cl (d) C6H6 + CH3COCl 6. Which one of the following substances is non-crystalline or amorphous? (a) Diamond (b) Graphite (c) Common Salt (d) Glass 7. Aspirin is an acetylation product of (b) o-hydroxybenzoic acid (a) p-dihydroxybenzene (c) o-dihydroxybenzene (d) m-hydroxybenzoic acid 8. Among the following, the least basic is (a) NH3 (b) AsH3 (c) PH3 (d) SbH3 9. 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 10. A compound formed by elements X and Y crystallizes 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 (d) XY2 (c) XY NBSE 2021 2

11. 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 12. The factor ∆Tb/Kb represents (b) normality (a) molality (c) formality (d) molarity 13. 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 14. In which of the following pairs, the two species are isostructural? (a) SF4 and XeF4 (b) BF3 and NF3 (c) BrO3– and XeO3 (d) SO32– and NO3– 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. The order of the following alkyl halides for SN2 reaction is (a) RF > RCl > RBr > RI (b) RF > RBr > RCl > RI (c) RCl > RBr > RF > RI (d) RI > RBr > RCl > RF 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. Among the given compounds, the interhalogen compound is (a) HClO4 (b) HCl (c) ClF3 (d) Cl2 21. What is the coordination number in a two-dimensional hexagonal close packed structure? (a) 2 (b) 6 (c) 4 (d) 8 NBSE 2021 3 [P.T.O.

22. Which of the following bonds has the highest energy? (a) Se-Se (b) Te-Te (c) S-S (d) O-O 23. Phenol is less acidic than (a) ethanol (b) o-nitrophenol (c) o-methylphenol (d) o-methoxyphenol 24. XeF6 on complete hydrolysis gives (a) Xe (b) XeOF­2 (c) XeO2 (d) XeO3 25. 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 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 HX C. R − OH + HX ZnCl2 → R − X + H2O CH3 CH3 CH3 + X2 DFaerk→ + D. (a) A XX (b) B (c) C (d) D 28. Which of the following species can act as the strongest base? (a) OH (b) OR (c) OC6H5 (d) O NO2 NBSE 2021 4

29. 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 30. The product formed when hot NaOH reacts with Cl2 is (a) NaOCl (b) NaClO3 (c) NaClO4 (d) NaClO2 31. Which of the following elements has highest electronegativity? (a) Br (b) Cl (c) F (d) I 32. 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 πr 3 3 3 (c) 12 πr 3 (d) 16 πr3 3 3 33. Which of the following reactions 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 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. A solution of acetone in ethanol (a) obeys Raoult’s law (b) shows a negative deviation from Raoult’s law (c) shows a positive deviation from Raoult’s law (d) behaves like a near ideal solution 36. Which of the following compounds will be most readily attacked by an electrophile? (a) Chlorobenzene (b) Benzene (c) Phenol (d) Toluene 37. 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 38. When NaCl crystal is doped with MgCl2, the nature of defect produced is (a) Interstitial (b) Schottky (c) Frenkel (d) Impurity NBSE 2021 5 [P.T.O.

39. An element has atomic mass 93 g mol–1 and density 11.5 g cm–3. If edge length of its unit cell is 300 pm, then which type of unit cell is formed by the element? (a) Primitive (b) BCC (c) FCC (d) HCP 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-Chlorobutane on reaction with alcoholic potash gives (a) but-1-ene (b) butan-1-ol (c) but-2-ene (d) butan-2-ol 42. 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 43. Number of atoms in one molecule of rhombic sulphur is (a) 3 (b) 4 (c) 8 (d) Infinite 44. C7H8 3C∆l2→ A Br2 /Fe→ B Zn/HCl→ C The compound C is (a) o-bromotoluene (b) m-bromotoluene (c) p-bromotoluene (d) 3-bromo-2,4,6-trichlorotoluene 45. 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. 46. 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. 47. 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. 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. 48. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): Schottky defect is generally shown by the compounds which have high coordination number. Reason(R): In Schottky defect, equal number of cations and anions are missing from the lattice sites. (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. (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 any 5. In case more than desirable number of questions are attempted, ONLY first 5 will be considered for evaluation. 50. Match the items of Column I and II and mark the correct option. Column I Column II A. Its partial hydrolysis does not change oxidation state of central (i) He atom B. It is used in modern diving apparatus (ii) XeF6 C. It is used to provide inert atmosphere for filling electrical bulbs (iii) XeF4 D. Its central atom is in sp3d2 hybridisation (iv) Ar (a) A-(i), B-(iv), C-(ii), D-(iii) (b) A-(i), B-(ii), C-(iii), D-(iv) (c) A-(ii), B-(i), C-(iv), D-(iii) (d) A-(i), B-(iii), C-(ii), D-(iv) 51. Which of the following analogies is correct? (a) Fibrous protein : Soluble in water : : Globular protein : Insoluble in water (b) Fibrous protein : Polypeptide chains coil in spherical shape : : Globular protein : Polypeptide chains run parallel (c) a-Helix : 2° structure of protein : : b-pleated sheet : 3° structure of protein (d) a-Helix : Hydrocarbon part (R) is large : : b-pleated sheet : Hydrocarbon part (R) is small. NBSE 2021 7 [P.T.O.

52. Complete the following analogy. Anti-Markovnikov addition of HBr is not observed : A : : Markovnikov addition of HBr is observed :B (a) A : Propene, B : But-1-ene (b) A : But-1-ene, B : But-2-ene (c) A: But-2-ene, B : But-1-ene (d) A : Pent-2-ene, B : Propene Case I: Read the passage given below and answer the following questions 53-55 Glucose (C6H12O6) contains six carbon atoms and an aldehyde group and is therefore referred to as an aldohexose. The glucose molecule can exist in an open-chain (acyclic) and ring (cyclic) form (in equilibrium), the latter being the result of an intramolecular reaction between the aldehyde C atom and the C-5 hydroxyl group to form an intramolecular hemiacetal. As the ring contains five carbon atoms and one oxygen atom, which resembles the structure of pyran, the cyclic form of glucose is also referred to as glucopyranose. In this ring, each carbon is linked to a hydroxyl side group with the exception of the fifth atom, which links to a sixth carbon atom outside the ring, forming a CH2OH group. (Source: Shendurse A.M., and Khedkar C.D. (2016) Glucose : Properties and Analysis. In: Caballero, B., Finglas, P., and Toldra F. (eds.). The Encyclopedia of Food and Health vol. 3, pp 239-247. Oxford: Academic Press.) 53. Which of the following carbohydrates is the C-2 epimer of glucose? (a) Fructose (b) Mannose (c) Galactose (d) Ribose 54. Which of the following reactions 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) 55. Which of the following compounds is the product formed when glucose reacts with H2/Ni? (a) Hexane (b) Hexanol (c) Sorbitol (d) Hexan-2-ol NBSE 2021 8