NBSE Question Papers Chemistry Term-1 (Set-2) for Class 12

Class 12  SET-2 Series NBSE/XII/2021 TERM-I Code No. 043/12/2 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. Elevation of boiling point was 0.52°C when 6 g of a compound X was dissolved in 100 g of water. Molecular weight of X is (Kb= 0.52 Km–1) (a) 120 kg/mol (b) 60 kg/mol (c) 180 kg/mol (d) 342 kg/mol 4. In Friedel-Crafts alkylation besides AlCl3 other reactants are (a) C6H6 + NH3 (b) C6H6 + CH4 (c) C6H6 + CH3Cl (d) C6H6 + CH3COCl 5. Li forms bcc crystals. The length of the side of a unit cell of Li is 351 pm. What is the atomic radius of Li? (a) 1.51 pm (b) 151.99 pm (c) 607 pm (d) 303 pm 6. Aspirin is an acetylation product of (a) p-dihydroxybenzene (b) o-hydroxybenzoic acid (c) o-dihydroxybenzene (d) m-hydroxybenzoic acid 7. The total number of tetrahedral voids in the face centred unit cell is (a) 6 (b) 8 (c) 10 (d) 12 8. Which of the following compounds is formed in the given reaction? Xe + F2 Ni-vessel→ (1 : 20 vol) (a) XeF2 (b) XeF4 (c) XeF6 (d) XeO3 9. 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 10. The factor ∆Tb/Kb represents (b) normality (a) molality (c) formality (d) molarity NBSE 2021 2

11. The reagents for the following conversion is/ are H Br ?→ H Br (a) Zn/CH3OH (b) alcoholic KOH followed by NaNH2 (c) aqueous KOH followed by NaNH2 (d) alcoholic KOH 12. The ionisation constant of phenol is higher than that of ethanol because (a) phenoxide ion is stronger base than ethoxide ion (b) phenoxide ion is stabilised through delocalisation. (c) phenoxide ion is less stable than ethoxide ion (d) phenoxide ion is bulkier than ethoxide ion 13. 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 14. In upper layer of the atmosphere, ozone is formed by (a) infrared rays action on O2 (b) high pressure on O2 (c) action of electric discharge on O2 (d) U.V. action on O2 15. By which bond the polypeptide chains are held together in fibrous protein? (a) Covalent bond (b) Hydrogen bond (c) Disulphide bond (d) Both (b) and (c) 16. Which of the following names is the correct IUPAC name of p-cresol? (a) Benzene-1, 4-diol (b) 4-Methylphenol (c) 4-Methyltoluene (d) Quinone 17. Which of the following is an example of aryl alkyl halide? (a) Benzyl chloride (b) Allyl chloride (c) Chlorobenzene (d) p-Chlorotoluene 18. 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 19. 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 20. Which of the following molecules have two different types of F – X – F angles (X = S, Xe, C)? (a) SF6 (b) CF4 (c) XeF4 (d) SF4 NBSE 2021 3 [P.T.O.

21. Which of the following bonds has the highest energy? (a) Se-Se (b) Te-Te (c) S-S (d) O-O 22. Phenol is less acidic than (a) ethanol (b) o-nitrophenol (c) o-methylphenol (d) o-methoxyphenol 23. XeF6 on complete hydrolysis gives (a) Xe (b) XeOF2 (c) XeO2 (d) XeO3 24. Which of the following is an example of aldohexose? (a) Sucrose (b) Glucose (c) Fructose (d) Lactose 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. 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. 27. The product formed when hot NaOH reacts with Cl2 is (a) NaOCl (b) NaClO3 (c) NaClO4 (d) NaClO2 28. A metallic element has cubic lattice. Edge length of unit cell is 2Å. The density of metal is 2.4 g cm–3. How many unit cells are present in 200 g of metal? (a) 1.04 × 1024 (b) 1.04 × 1023 (c) 6.023 × 1023 (d) 1.04 × 1025 29. 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 30. Which of the following reactions is a halogen exchange reaction? A. RX + NaI → RI + NaX NBSE 2021 4

B. C = C + HX → C — C HX C. R − OH + HX ZnCl2 → R − X + H2O CH3 CH3 CH3 + X2 DFaerk→ + D. XX (a) A (b) B (c) C (d) D 31. The basic character of the hydrides of V group (group 15) elements decreases in the order (a) NH3 > PH3 > AsH3 > SbH3 (b) SbH3 > AsH3 > PH3 > NH3 (c) NH3 > SbH3 > PH3 > AsH3 (d) SbH3 > PH3 > AsH3 > NH3 32. 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 33. 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 34. T otal volume of atoms present in a face centred cubic unit cell of a metal is (r is atomic radius) (a) 20 πr3 (b) 24 πr 3 3 3 (c) 12 πr3 (d) 16 πr 3 3 3 35. The glucose solution to be injected into the blood stream and the blood itself should have the same (a) viscosity (b) vapour pressure (c) molarity (d) osmotic pressure 36. W hen NaCl crystal is doped with MgCl2, the nature of defect produced is (a) Interstitial (b) Schottky (c) Frenkel (d) Impurity 37. Which of the following compounds will be most readily attacked by an electophile? (a) Chlorobenzene (b) Benzene (c) Phenol (d) Toluene 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 NBSE 2021 5 [P.T.O.

39. The structure of SO2 is (b) tetrahedral (a) angular (c) planar (d) linear 40. I n 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 41. Number of atoms in one molecule of rhombic sulphur is (a) 3 (b) 4 (c) 8 (d) Infinite 42. C 7H8 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 43. W hich 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 44. 1-Chlorobutane on reaction with alcoholic potash gives (a) but-1-ene (b) butan-1-ol (c) but-2-ene (d) butan-2-ol 45. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A) : F2 has low reactivity. Reason (R): F-F bond has low ∆bondH°. (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. (a) Both A and R are true and R is the correct explanation A. NBSE 2021 6

(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): The O-O bond length in ozone is identical with that in molecular oxygen. Reason(R): The ozone molecule is a resonance hybrid of two canonical structures. (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. Kolbe’s Reaction (i) Heated copper at 578 K B. Conversion of 2°-alcohol to ketone (ii) Conversion of phenol to o-hydroxy salicylic acid C. Williamson’s synthesis (iii) 4-Nitro-3-methylphenol D. Mononitration of m-cresol ( iv) Reaction of RX with R'ONa (a) A-(iv), B-(i), C-(ii), D-(iii) (b) A-(ii), B-(i), C-(iv), D-(iii) (c) A-(iii), B-(ii), C-(i), D-(iv) (d) A-(iv), B-(iii), C-(ii), D-(i) 51. Which of the following analogy is correct? (a) Henry’s law : psolute = KH.msolute : : Raoult’s law : psolute = msolute  ps0olute (where, p = partial pressure of component in solution, KH = Henry’s constant, m = molality, p0 = partial pressure in pure state) NBSE 2021 7 [P.T.O.

(b) Lowering of vapour pressure : Not a colligative property : : Osmotic pressure : Colligative property (c) Molality : Depends on temperature : : Molarity : Independent of temperature (d) Kf : Ebullioscopic constant : : Kb : Cryoscopic constant. 52. Complete the following analogy. Aliphatic Alcohols : A : : Phenols : B (a) A : More acidic, B : Less acidic (b) A : Partial double bond character in C—O bond, B : No partial double bond character in C—O bond (c) A: Do not react with NaHCO3 solution, B : React with NaHCO3 solution (d) A : Do not give any purple colour with neutral FeCl3 solution, B : Gives purple colour with neutral FeCl3 solution. Case I: Read the passage given below and answer the following questions 53-55 a-Alanine molecules display an optical rotatory ability, that is the ability of the molecules to rotate the plane of the polarised light, either to the left or to the right. The ability can be attributed to the fact that a-carbon atom of this molecule attaches to four different groups. H | H3Cβ  Cα  CO2H | NH2 Due to this attachment, a-alanine is categorised as an asymmetric molecule, because it does not possess complete symmetry when viewed from a purely geometrical standpoint. The asymmetric structure means that the two structures relate to each other as an object to its mirror image or the right hand to the left. As a consequence of this structural variation, two tetrahedral arrangements of the groups about the asymmetric a-carbon atom attached, that are proposed for, respectively, the D- and L-a-alanine structures, also relate to each other as an object to its mirror image. Thus, if equal amounts of these mirror image molecules (D- and L-) are put together, the result is DL-a-alanine compound that has neutral optical effect due to the cancellation from the constituent isomer’s optical effect. (Source: Frida U. Ermawati. Optical Activity of an Asymmetric Substance. Jurnal Fisika Dan Aplikasinya Volume 6, Nomor 1 Januari, 2010) 53. The side chain, –R in alanine is (a) –CH3 (b) –CH2CH3 (c) –CH(CH3)2 (d) –H 54. Which of the following statements is correct? (a) L-Alanine is represented by –NH2 group on right side. (b) Alanine forms zwitter ion which has negative charge on –NH2 group. (c) ‘D’ in D-Alanine shows dextrorotatory nature. (d) An equimolar mixture of D- and L-Alanine is a racemic mixture. 55. An asymmetric carbon must be hybridised as (a) sp2 (b) sp3 (c) sp (d) dsp2 NBSE 2021 8