CBSE Class 12 Chemistry Sample Paper Solution | 2021-22

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November 05, 2021

1.Which of the following statements is true:

(a)Melting point of Phosphorous is less than that of Nitrogen

(b)`N_{2}` is highly reactive while `P_{4}` is inert

(c)Nitrogen shows higher tendency of catenation than P

(d)N-N is weaker than P-P

2. Which of the following is a non-stoichiometric defect?

(a)Frenkel defect

(b)Schottky defect

(c)metal deficiency defect

(d)interstitial defect

3. Identify the law which is stated as: “For any solution, the partial vapour pressure of each volatile component in the solution is directly proportional to its mole fraction.”

(a)Henry’s law

(b) Raoult’s law

(c)Dalton’s law

(d)Gay-Lussac's Law

4. Pink colour of LiCl crystals is due to:

(a) Schottky defect

(b)Frenkel defect

(d) Metal deficiency defect

5. Which of the following isomer has the highest meltingpoint:

(a) 1,2-dicholorbenzene

(b) 1,3 -dichlorobenzene

(d) all isomers have same melting points

6. Which one of the following reactions is not explained by the open chain Structureof glucose:

(a) Formation of pentaacetate of glucose with acetic anhydride.

(b) formation of addition product with 2,4 DNP reagent

(d) existence of alpha and beta forms of glucose.

7. Williamson’s synthesis of preparing dimethyl ether is an:

(a) `"SN"^{1}` reaction

(b) Elimination reaction

(d) Nucleophilic addition reaction

8. Chlorine water loses its yellow colour on standing because:

(a) HCl gas is produced, due to the action of sunlight.

(b) a mixture of HOCl and HCl is produced in the presence of light

(d) a mixture of HCl and ClO3 is produced, due to the action of sunlight

9. During dehydration of alcohols to alkenes by heating with concentrated `"H"_{2}"SO"_{4}`, the initiation step is:

(a) protonation of alcohol molecule

(b) formation of carbocation

(d) formation of an ester

10. Amorphous solids are:

(a) isotropic

(b)anisotropic

(d) isomeric

11. Which of the following reactions is used to prepare salicylaldehyde?

(a) Kolbe’s reaction

(b) Etard reaction

(d) Stephen’s reduction.

12. Which of the following is an example of a solid solution?

(a)sea water

(b)sugar solution

(c)smoke

(d)22 carat gold

13. The boiling points of alcohols are higher than those of hydrocarbons of comparable masses due to:

(a) Hydrogen bonding

( b) Ion – dipole interaction

(d) Van der Waal’s forces.

14. Which of the following has the lowest boiling point:

(a)`"H"_{2}"O"`

(b)`"H"_{2}"S"`

(c)`"H"_{2}"Se"`

(d)`"H"_{2}"Te"`

15. Which of the following statement is correct:

(a)Fibrous proteins are generally soluble in water

(b)Albumin is an example of fibrous proteins

(c)In fibrous proteins, the structure is stabilised by hydrogen bonds and disulphide bonds

(d)pH does not affect the primary structure of protein.

16. Major product obtained on reaction of 3-Phenyl propene with HBr in presence of organic peroxide

(a)3- Phenyl 1- bromopropane
(b) 1 –Phenyl -3- bromopropane
(c) 1-Phenyl -2-bromopropane
(d) 3-Phenyl -2- bromopropane

17. Which of the following is a correct statement for `"C"_{2}"H"_{5}`Br?

(a) It reacts with metallic Na to give ethane.

(b) It gives nitroethane on heating with aqueous solution of `"AgNO"_{2}`

(d) It forms diethylthioether on heating with alcoholic KSH.

18. Covalency of nitrogen is restricted to:

(a)2

(b)3

(d)5

19.Solubility of gases in liquids decreases with rise in temperature because dissolution is an:

(a)endothermic and reversible process

(b)exothermic and reversible process

(c)endothermic and irreversible process

(d) exothermic and irreversible process

20. All elements of Group 15 show allotropy except:

(a)Nitrogen

(b)Arsenic

(c)Antimony

(d)Bismuth

21.Which of the following is a polysaccharide?

(a)glucose

(b)maltose

(c)glycogen

(d)lactose

22. Substance having the lowest boiling point:

(a)Hydrogen

(b)Oxygen

(c)Nitrogen

(d) Helium

23.Lower molecular mass alcohols are:

(a)miscible in limited amount of water

(b) miscible in excess of water

(d) immiscible in water

24.Maximum oxidation state exhibited by Chlorine is:

(a) +1

(b) +3

(c)+5

(d)+7

25. In which of the following cases blood cells will shrink:

(a)when placed in water containing more than 0.9% (mass/ volume) NaCl solution.

(b)when placed in water containing less than 0.9% (mass /volume) NaCl solution.

(c)when placed in water containing 0.9% (mass/volume) NaCl solution.

(d)when placed in distilled water.

26. How much ethyl alcohol must be added to 1 litre of water so that the solution will freeze at– 14°C ? (Kf for water = 1.86°C/mol)

(a) 7.5 mol

(b)8.5 mol

(d)10.5 mol

27. Which reagents are required for one step conversion of chlorobenzene to toluene?

(a) CH3Cl / AlCl3

(b) CH3Cl, Na, Dry ether

(c)CH3Cl/Fe dark

(d) NaNO2/ HCl /0-50C

28. On partial hydrolysis, XeF6 gives:

(a) XeO3 +4HF

(b) XeO2F + HF

(d) XeO2F2 + 4HF

29. Which one of the following statement is correct about sucrose :

(a) It can reduce tollen’s reagent however cannot reduce fehling’s reagent

(b) It undergoes mutarotation like glucose and fructose

(d) It is laevorotatory in nature .

30. Phenol does not undergo nucleophilic substitution reaction easily due to:

(a) acidic nature of phenol

(b) partial double bond character of C-OH bond

(d)instability of phenoxide ion

31. Which of the following has highest ionisation enthalpy?

(a)Nitrogen

(b)Phosphorus

(c)Oxygen

(d)Sulphur

32. Metal M ions form accp structure. Oxide ions occupy ½ octahedral and ½ tetrahedral voids. What is the formula of the oxide?

(a)MO

(b)M`"O"_{2}`

(c)M`"O"_{3}`

(d) `"M"_{2}``"O"_{3}`

33. The reaction of toluene with C`"l"_{2}` in presence of FeC`"l"_{3}` gives ‘X’ while theof toluene with C`"l"_{2}` in presence of light gives ‘Y’. Thus ‘X’ and ‘Y’are:

(a) X = benzyl chloride Y = o and p – chlorotoluene

(b) X = m – chlorotoluene Y = p – chlorotoluene

(d) X= benzyl chloride, Y = m-chlorotoluene

34.Ozone is a/ an __________ molecule and the two O-O bond lengths in ozone are (i)_______-and (ii) ____________

(a) linear ,110pm ; 148pm

(b) angular, 110pm ; 148pm

(c)linear, 128pm ; 128pm

(d)angular, 128pm ; 128pm

35. Water retention or puffiness due to high salt intake occurs due to:

(a)diffusion

(b)vapour pressure difference

(d)reverse osmosis

36. In the following reaction,identify A and B

(a) A= COOH-`("CH"_{2})_{4}` -COOH, B= OHC-(CHOCO`"CH"_{3})_{4}` -`"CH"_{2}`OCO`"CH"_{3}`

(b) A= COOH-`("CH"_{2})_{4}` -CHO , B= OHC-(CHOCO`"CH"_{3})_{4}` -`"CH"_{2}`OCO`"CH"_{3}`

(d) A= OHC-(CHOCOC`"H"_{3})_{4}`-C`"H"_{2}`OCOC`"H"_{3}` B= COOH-(C`"H"_{2})_{4}` -COOH

37. In lake test for Al3+ ions, there is the formation of coloured ‘floating lake’. It is due to:

(a)Absorption of litmus by [`"Al(OH)"_{4}`] -
(b)Absorption of litmus by `"Al(OH)"_{3}`
(c)Adsorption of litmus by [`"Al(OH)"_{4}`] -
(d) Adsorption of litmus by Al`"(OH)"_{4}`

38. A unit cell of NaCl has 4 formula units. Its edge length is 0.50 nm. Calculate the density if molar mass of NaCl = 58.5 g/mol.

(a) 1 g/`"cm"^{3}`

(b)2 g/`"cm"^{3}`

(d)4 g/`"cm"^{3}`

39.Which one of the following are correctly arranged on the basis of the property indicated:

(a)I2< Br2<F2<Cl2 [ increasing bond dissociation enthalpy]
(b) H2O > H2S<H2Te<H2Se [ increasing acidic strength]
(c) NH3 < N2O< NH2OH<N2O5 [ increasing oxidation state]
(d) BiH3<SbH3<AsH3<PH3<NH3 [ increasing bondangle]

40. What would be the reactant and reagent used to obtain 2,. 4-dimethyl pentan-3-oI?

(a) Propanal and propyl magnesium bromide

(b) 3-methylbutanal and 2-methyl magnesium

(d) 2- methylpropanal and isopropyl magnesium iodide

41.o-hydroxy benzyl alcohol when reacted with PCl3 gives the product as (IUPAC name)

(a) o- hydroxy benzyl chloride

(b) 2- chloromethylphenol

(d) 4-hydroxymethylphenol

42. Which of the following statements is true:

(a) Ammonia is the weakest reducing agent and the strongest base among Group 15 hydrides.

(b) Ammonia is the strongest reducing agent as well as the strongest base among Group 15 hydrides.

(d) Ammonia is the strongest reducing agent and the weakest base among Group 15 hydrides.

43.Identify the secondary alcohols from the following set:

(i)CH3CH2CH(OH)CH3

(ii) (C2H5)3COH

(iii)

(a)(i) and (iv)

(b)(i) and (iii)

(c)(i) and (ii)

(d)(i), (iii) and (iv)

44. Alkenes decolourise bromine water in presence of CCl4 due to formation of:

(a) allyl bromide

(b) vinyl bromide

(d) vicinal dibromide

45. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion (A): Electron gain enthalpy of oxygen is less than that of Flourine but greater than Nitrogen.

Reason (R): Ionisation enthalpies of the elements follow the order Nitrogen > Oxygen > Fluorine

Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not the correct explanation of A.

(d) A is false but R is true.

46. Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion (A): Alkyl halides are insoluble in water.

Reason (R): Alkyl halides have halogen attached to sp3 hybrid carbon. Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of 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): Molarity of a solution changes with temperature.

Reason (R): Molarity is a colligative property. Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of 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):SO2 is reducing while TeO2 is an oxidising agent.

Reason(R):Reducing property of dioxide decreases from SO2 to TeO2. Select the most appropriate answer from the options given below: (a) Both A and R are true and R is the correct explanation of 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):Cryoscopic constant depends on nature of solvent. Reason(R ):Cryoscopic constant is a universal constant. Select the most appropriate answer from the options given below:

(a) Both A and R are true and R is the correct explanation of 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.

50. Match the following:

I	II
(i)Amino acids	(A)protein
(ii)Thymine	(B)Nucleic acid
(iii)Insulin	( C)DNA
(iv)phosphodiester linkage	(D)Zwitter ion
(v) Uracil	v

Which of the following is the best matched options?

(a) i-A, v- D, iii- C, iv-B

(b) i-D, ii-C, iii- A, iv-B

(d) i-A, ii- C, iii- D, iv-B

51. Which of the following analogies is correct:

(a)Nitrogen: 1`"s"^{2}` 2`"s"^{2}` 2`"p"^{3}` :: Argon:1`"s"^{2}` 2`"s"^{2}` 2`"p"^{6}`

(b)Carbon: maximum compounds :: Xenon: no compounds

(d)Helium: meteorological observations:: Argon: metallurgical processes

52. Complete the following analogy: Same molecular formula but different structures: A:: Non superimposable mirror images: B

(a) A:Isomers B: Enantiomer

(b) A: Enantiomers B: Racemic mixture

(d) A: IsomersB: Sterioisomers

CASE1: Read the passage given below and answer the following questions

Early crystallographers had trouble solving the structures of inorganic solids using X-ray diffraction because some of the mathematical tools for analyzing the data had not yet been developed. Once a trial structure was proposed, it was relatively easy to calculate the diffraction pattern, but it was difficult to go the other way (from the diffraction pattern to the structure) if nothing was known a priori about the arrangement of atoms in the unit cell. It was important to develop some guidelines for guessing the coordination numbers and bonding geometries of atoms in crystals. The first such rules were proposed by Linus Pauling, who considered how one might pack together oppositely charged spheres of different radii. Pauling proposed from geometric considerations that the quality of the "fit" depended on the radius ratio of the anion and the cation.
If the anion is considered as the packing atom in the crystal, then the smaller cation fills interstitial sites ("holes"). Cations will find arrangements in which they can contact the largest number of anions.

If the cation can touch all of its nearest neighbour anions then the fit is good. If the cation is too small for a given site, that coordination number will be unstable and it will prefer a lower coordination structure. The table below gives the ranges of cation/anion radius ratios that give the best fit for a given coordination geometry.

Coordination number	Geometry	ρ = `r_{cation}`/ranion
2	linear	0 – 0.155
3	triangular	0.155 – 0.225
4	tetrahedral	0.225 – 0.414
4	square planar	0.414 – 0.732
6	octahedral	0.414 – 0.732
8	cubic	0.732 – 1.0
12	cuboctahedral	1.0