Class 12 Chemistry: CBSE Sample Question Paper- Term I (2021-22)- 4 | Sample Papers for Class 12 Medical and Non-Medical PDF Download

Class-XII

Max. 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.

Section - A

Q.1: Anoxia is a condition related to people who ? 
(a) are divers 
(b) climb high altitudes 
(c) live in snowy region 
(d) are obese

Correct Answer is Option (b)

Anoxia is a condition which leads to low concentrations of oxygen in the blood and tissues of people living at high altitudes or climbers. Low blood oxygen causes climbers to become weak and unable to think clearly, symptoms of a condition known as anoxia.

Q.2: _____________ is an antifreeze used in cars for cooling the engine. 
(a) ethane glycol 
(b) methylene glycol 
(c) ethylene glycol 
(d) none of the above

Correct Answer is Option (c)

Ethylene glycol is an antifreeze used in cars for cooling the engine.

Q.3: The correct order for increase in density is: 
(a) n-C₃H₇I < n-C₃H₇Cl < n- C₃H₇Br 
(b) n-C₃H₇I < n-C₃H₇Br < n-C₃H₇Cl 
(c) n-C₃H₇Cl < n- C₃H₇Br < n-C₃H₇I 
(d) n- C₃H₇Br < n-C₃H₇I < n-C₃H₇Cl

Correct Answer is Option (a)

It depends on conc. of only one reactant, t-butyl chloride.

Q.4: Used as a diluent for oxygen in modern diving apparatus: 
(a) neon 
(b) liquid helium 
(c) argon 
(d) liquid nitrogen

Correct Answer is Option (b)

Liquid helium is used as a diluent for oxygen in modern diving apparatus because of its very low solubility in blood.

Q.5: Choose the correct product for the given reaction:

(a) 

(b) 

(c) 

(d) 

Correct Answer is Option (c)

Alcohols react with active metals such as aluminium to yield corresponding alkoxides and hydrogen.

Q.6: Which of the following do not show allotropy ? 
(a) Nitrogen 
(b) Phosphorus 
(c) Arsenic
(d) All of the above

Correct Answer is Option (a)

Except nitrogen, all the other group 15 elements show allotropy.

Q.7: In which pair most efficient packing is present? 
(a) hcp and bcc 
(b) hcp and ccp 
(c) bcc and ccp 
(d) bcc and simple cubic

Correct Answer is Option (b)

hcp and ccp has 74% packing efficiency i.e. 74% of the space in filled.

Q.8: When there are no unpaired electrons the substance shows __________ while with one or more unpaired electrons, the substance shows ______________:
(a) diamagnetism, paramagnetism 
(b) paramagnetism, diamagnetism 
(c) ferromagnetism, diamagnetism 
(d) diamagnetism, ferromagnetism

Correct Answer is Option (a)

The substances having paired electrons are diamagnetic in nature while those having unpaired electrons are paramagnetic in nature.

Q.9: The dinitrogen gas after preparation is passed through aqueous sulphuric acid containing potassium dichromate to remove: 
(a) NO₂ and H₂SO₄ 
(b) NO and HCl 
(c) NO and HNO₃ 
(d) NO₂ and HNO₃

Correct Answer is Option (c)

NO and HNO₃ are the impurities formed during the preparation of dinitrogen and are removed by passing the gas through aqueous sulphuric acid containing potassium dichromate.

Q.10: Which of the following shows nucleophilic substitution by S_N¹ mechanism:
(a) 

(b) 

(c) 

(d) 

Correct Answer is Option (a)

As it is tertiary halide, the carbo cation formed will be more stable.

Q.11: Aniline on treatment with nitrous acid at 273-278 K gives: 
(a) benzene amide 
(b) benzene diazonium chloride 
(c) benzene peroxide 
(d) benzene diazonium oxide

Correct Answer is Option (b)

Benzene diazonium chloride is formed which is hydrolysed to phenols by warming with water.

Q.12: Supersonic jet aeroplanes are responsible for depleting the conc. of ozone layer because: 
(a) they emit nitrogen oxides. 
(b) nitrogen oxides readily combine with ozone. 
(c) none of the above 
(d) both (a) and (b)

Correct Answer is Option (d)

Nitrogen oxides emitted from the exhaust systems of supersonic jet aeroplanes is slowly depleting the concentration of the ozone layer in the upper atmosphere as nitrogen oxides (particularly nitrogen monoxide) combine very rapidly with ozone.

Q.13: When hydrochloric acid reacts with ammonia __________ is produced: 
(a) white fumes of NH₄OH 
(b) white fumes of NH₄Cl 
(c) hydrogen gas 
(d) chlorine gas

Correct Answer is Option (b)

Hydrochloric acid reacts with ammonia and ionise into ammonium ion and chloride ion which further combines to form white fumes of NH₄Cl.

NH₃(aq) + HCl(aq) → NH₄ +(aq)+ Cl^- (aq) NH₄ +(aq) + Cl^- (aq) → NH₄Cl(g)

Q.14: When measured along different directions in the same crystals some properties like refractive index and electrical resistance have different values. This nature of solids are known as: 
(a) Anisotropic 
(b) Isotropic 
(c) Pseudo solids 
(d) None of the above

Correct Answer is Option (a)

Q.15: Which of the following is incorrectly paired ? 
(a) chloramphenicol – dengue fever 
(b) chloroquine – malaria 
(c) halothane – surgery 
(d) thyroxine – goiter

Correct Answer is Option (a)

Chloramphenicol is helpful in treatment of typhoid fever.

Q.16: The acid strength of alcohol is:

(a) 

(b) 

(c) 

(d) 

Correct Answer is Option (d)

Acid strength decreases in the order given.

Q.17: Chlorobenzene is fused with NaOH at 623 K and 320 atmospheric pressure. Sodium phenoxide thus obtained undergoes _______ to obtain phenol.
(a) hydrolysis 
(b) hydrogenation 
(c) acidification 
(d) neutralisation

Correct Answer is Option (c)

Acidification using HCl converts sodium phenoxide to phenol.

Q.18: In S_N² reactions tertiary halides are least reactive due to: 
(a) halide group 
(b) three hydrogen atoms 
(c) three methyl group 
(d) conc. of halide group

Correct Answer is Option (c)

Methyl groups are bulky group which hinders the approaching nucleophile.

Q.19: Which of the following is the correct order ? 
(a) N₂O –basic oxide 
(b) Al₂O₃ – neutral oxide 
(c) Na₂O - amphoteric oxide 
(d) CrO₃ – acidic oxide

Correct Answer is Option (d)

CrO₃ is an acidic oxide. This is because metals in high oxidation state form acidic oxide.

Q.20: The correct order of increasing the reactivity of C—X bond towards nucleophile in following compounds:

(a) IV < III < II < I 
(b) I < II < III < IV 
(c) III < II < I < IV 
(d) II < III < I < IV

Correct Answer is Option (c)

III is most reactive due to stability of tertiary carbo cation.
-NO₂ (electron withdrawing groups increases nucleophilic substitution reaction.

Q.21: Which of the following is an ambident nucleophile ? 
(i) cyanides 
(ii) hydroxyl 
(iii) nitrites 
(a) (i), (ii) 
(b) (i), (ii), (iii) 
(c) (i), (iii) 
(d) (ii), (iii)

Correct Answer is Option (c)

As it can link through carbon or nitrogen atom (as in case of cyanide) or through nitrogen or oxygen atom as in nitrites, it is called as ambident nucleophile.

Q.22: The presence of strong hydrogen bonding in H2O as compare to H2S is due to: 
(a) small size of oxygen 
(b) high electronegativity in O 
(c) low electronegativity in O 
(d) both (a) and (b)

Correct Answer is Option (d)

The anomalous behaviour like, strong hydrogen bonding in H2O is due to small size and high electro-negativity of oxygen.

Q.23: Which of the following solutions possess lowest freezing point? 
(a) 1 M KCl 
(b) 1 M K₂SO₄ 
(c) 1 M glucose 
(d) 1 M Urea

Correct Answer is Option (b)

Depression in freezing point is colligative property and it depends upon the number of particles or ions. Greater the number of ions in solution, lesser will be the freezing point.
Since, 1 M K₂SO₄ dissociates into three ions, so, its freezing point will be lowest.

Q.24: Which of the following compounds does not exist ? 

(a) NeF₂ 
(b) XeF₂ 
(c) XeO₃ 
(d) XeOF₄

Correct Answer is Option (a)

NeF₂ does not exist because the first and second ionization enthalpies of Ne as very light.

Q.25: Ethanol on heating with conc. sulphuric acid at 170˚C gives: 
(a) Ethyl hydrogen sulphate 
(b) Diethyl ether 
(c) Diethyl sulphate 
(d) Ethylene

Correct Answer is Option (d)

Section - B

Q.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
(c) 9.5 mol
(d) 10.5 mol

Correct Answer is Option (a)

7.5 mol

ΔT_f = K_f m

Q.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 /0-5°C

Correct Answer is Option (b)

Q.28: On partial hydrolysis, XeF₆ gives: 
(a) XeO₃ +4HF 
(b) XeO₂F + HF 
(c) XeOF₄+ 2HF 
(d) XeO₂F₂ + 4HF

Correct Answer is Option (c)

The reaction involved in the partial hydrolysis is:

Q.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 
(c) It undergoes inversion in the configuration on hydrolysis 
(d) It is laevorotatory in nature.

Correct Answer is Option (c)

It undergoes inversion in the configuration on hydrolysis.

Q.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 
(c) Partial double bond character of C-C bond 
(d) Instability of phenoxide ion

Correct Answer is Option (b)

Phenol does not undergo nucleophilic substitution reaction due to partial double bond character of C-OH bond. It is due to the fact that the oxygen gets attached to the carbon on the benzene ring acquires a partial double bond character by means of resonance(+R) effect, making it difficult to break.

Q.31: Which of the following has highest ionisation enthalpy? 
(a) Nitrogen 
(b) Phosphorus 
(c) Oxygen 
(d) Sulphur

Correct Answer is Option (a)

High IE of N is because of smallest size in the group and completely half - filled p-subshell.

Q.32: Metal M ions form a ccp structure. Oxide ions occupy ½ octahedral and ½ tetrahedral voids. What is the formula of the oxide? 
(a) MO 
(b) MO₂ 
(c) MO₃ 
(d) M₂O₃

Correct Answer is Option (d)

Metal M ions form ccp structure. Let number of ions of M be : X
No. of tetrahedral voids = 2x
No. of octahedral voids = x
Number of oxide ions will be ½ x + ½ (2x) = 3/2 x
Formula of oxide = M_xO_3/2x = M₂O₃

Q.33: The reaction of toluene with Cl₂ in presence of FeCl₃ gives ‘X’ while the toluene with Cl₂ 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 
(c) X = o and p–chlorotoluene Y = trichloromethyl benzene 
(d) X= benzyl chloride, Y = m-chlorotoluene

Correct Answer is Option (c)

The reaction of toluene with Cl₂ in presence of FeCl₃ gives ‘X’ due to electrophilic substitution reaction taking place at ortho and para positions and the reaction taking place in the presence of light gives ‘Y’, due to substitution reaction occurring via free radical mechanism. Thus ‘X’ and ‘Y’are X = o and p–chlorotoluene, Y = trichloromethylbenzene.

Q.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

Correct Answer is Option (d)

Ozone is a resonance hybrid of two equivalent structures.

Q.35: Water retention or puffiness due to high salt intake occurs due to: 
(a) Diffusion
(b) Vapour pressure difference 
(c) Osmosis 
(d) Reverse osmosis

Correct Answer is Option (c)

High salt intake retains extra sodium in the body which increases the amount of fluid (water) in the body, outside of the cells. It occurs due to osmosis (it is the spontaneous net movement of solvent molecules through a selectively permeable membrane from a region of high water concentration to a region of low water concentration).

Q.36: In the following reaction, identify A and B:

(a) A= COOH-(CH₂)₄-COOH, B= OHC-(CHOCOCH₃)₄-CH₂OCOCH₃ 
(b) A= COOH-(CH₂)₄ -CHO, B=OHC-(CHOCOCH₃)₄ -CH₂OCOCH₃ 
(c) A= OHC-(CHOCOCH₃)₃-CH₂OCOCH₃ B=COOH-(CH₂)₄ -CHO, 
(d) A= OHC-(CHOCOCH₃)₄-CH₂OCOCH₃ B=COOH-(CHOH)₄-COOH

Correct Answer is Option (d)

Q.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)₃

Correct Answer is Option (d)

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

Q.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/cm³ 
(b) 2 g/cm³ 
(c) 3 g/cm³ 
(d) 4g/cm³

Correct Answer is Option (c)

3 g/cm³
Using formula

Q.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 bond angle]

Correct Answer is Option (d)

BiH₃ < SbH₃ < AsH₃ < PH₃ < NH₃ [ increasing bond angle ] correct order.
(a) I₂ < Br₂<F₂<Cl₂ [increasing bond dissociation enthalpy]: incorrect order , correct order is Cl₂ > Br₂ > F₂ > I₂.
(b) H₂O > H₂S<H₂Te<H₂Se [increasing acidic strength]: incorrect order, correct order is H₂O<H₂S<H₂Se<H₂Te
(c) NH₃ < N₂O< NH₂OH < N₂O₅ [ increasing oxidation state ] : incorrect order NH₃ (Oxidation state -3) N₂O (Oxidation state +1) NH₂OH(Oxidation state -1) N₂O₅ (Oxidation state +5).

Q.40: What would be the reactant and reagent used to obtain 2, 4-dimethyl pentan-3-ol ? 
(a) Propanal and propyl magnesium bromide 
(b) 3-methylbutanal and 2-methyl magnesium iodide 
(c) 2-dimethylpropanone and methyl magnesium iodide 
(d) 2- methylpropanal and isopropyl magnesium iodide

Correct Answer is Option (d)

Q.41: o-hydroxy benzyl alcohol when reacted with PCl₃ gives the product as (IUPAC name)
(a) o- hydroxy benzyl chloride 
(b) 2- chloromethylphenol 
(c) o-chloromethylchlorobenzene 
(d) 4-hydroxymethylphenol

Correct Answer is Option (b)

Due to occurrence of the under given reaction:

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

Correct Answer is Option (a)

Ammonia is the weakest reducing agent and the strongest base among Group 15 hydrides.
The reducing character of hydrides increases down the group due to decrease in bond dissociation enthalpy.

Q.43: Identify the secondary alcohols from the following set:

(i) CH₃CH₂CH(OH) CH₃ 
(ii) (C₂H₅)₃COH
(iii)
(iv)

(a) (i) and (iv) 
(b) (i) and (iii) 
(c) (i) and (ii) 
(d) (i), (iii)and (iv)

Correct Answer is Option (a)

(i) CH₃CH₂CH(OH)CH₃ (secondary)

(ii) (C₂H₅)₃COH (tertiary)

Q.44: Alkenes decolourise bromine water in presence of CCl₄ due to formation of: (a) Allyl bromide 
(b) Vinyl bromide 
(c) Bromoform 
(d) Vicinal dibromide

Correct Answer is Option (d)

CH₂ = CH₂ + Br₂ → BrCH₂ - CH₂Br.

Q.45: Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

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.
(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 and R is true.

Correct Answer is Option (c)

Ionisation enthalpies of the elements follow the order Fluorine >Nitrogen > Oxygen

Q.46: Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Alkyl halides are insoluble in water.
Reason (R) : Alkyl halides have halogen attached to sp³ hybrid carbon.
(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 and R is true.

Correct Answer is Option (b)

Alkyl halides are insoluble in water because they are unable to form hydrogen bonds with water or break preexisting hydrogen bonds.

Q.47: Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion(A): Molarity of a solution changes with temperature. 
Reason (R): Molarity is a colligative property.
(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 and R is true.

Correct Answer is Option (c)

Molarity is a means to express concentration. It is not a physical property.

Q.48: Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion(A): SO₂ is reducing agent while TeO₂ is an oxidising agent.
Reason(R): Reducing property of dioxide decreases from SO₂ to TeO₂.
(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 and R is true.

Correct Answer is Option (a)

Q.49: Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Cryoscopic constant depends on nature of solvent. 
Reason(R): Cryoscopic constant is a universal constant.
(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 and R is true.

Correct Answer is Option (c)

Cryoscopic constant various with type of solvent.

Section - C

Q.50: Match the following:

Which of the following is the best matched options ?
(a) i-B, v-C, iii-A, iv-D
(b) i-B, ii-A, iii-D, iv-C

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

Correct Answer is Option (c)

Ethanol undergoes elimination reaction when heated with conc. H2SO4 and gives ethene. Glycol - It is dihydric alcohol.

Acetic acid reacts with ethanol in acidic medium to form an ester. This reaction is called esterification.
Methoxyethane = CH₃OCH₂CH₃ 
Since it contains two different alkyl groups so it is called mixed ether.

Q.51: Complete the following analogy: 
Glucose: A:: Fructose: B 
(a) A: -NH₂; B: -CHO 
(b) A: >C=O ; B: -CHO 
(c) A: -CHO; B: >C=O 
(d) A: -CONH2;B: -OH

Correct Answer is Option (c)

The functional groups present in glucose and fructose are -CHO and >C=O respectively.

Q.52: Which of the following analogies is correct: 

(a) Group 15: Carfon family:: Group 16: Oxygen family 
(b) Rhomfic sulphur: α-sulpher:: Monoclinic sulpher: β-sulpher 
(c) Caro’s acid: H₂SO₃:: Oleum: H₂S₂O₇ 
(d) Halide ion: Cl-:: Pseudohalide ion: OH^-

Correct Answer is Option (b)

There are two allotropics of sulphur viz Rhombic sulphur (α-sulphur) and Monoclinic sulphur (β-sulphur)

Read the passage given below and answer the following questions 53-55

Aryl halides are extremely less reactive towards nucleophilic substitution reactions due to the following reasons: 
(i) In haloarenes, the electron pairs on halogen atom are in conjugation with π-electrons of the ring. 
(ii) In haloalkane, the carbon atom attached to halogen is sp³ hybridised while in case of haloarene, the carbon atom attached to halogen is sp² -hybridised. 
(iii) In case of haloarenes, the phenyl cation formed as a result of self-ionisation will not be stabilised by resonance.

Q.53: A primary alkyl halide would prefer to undergo ________. 
(a) S_N¹ reaction 
(b) S_N² reaction 
(c) α-Elimination 
(d) Racemisation

Correct Answer is Option (b)

A primary alkyl halide would prefer to undergo S_N² reaction

Q.54: What is ‘A’ in the following reaction ?

(a) 
 

(b) 
 

(c)

(d) 

Correct Answer is Option (c)

Q.55: Which of the following alkyl halides will undergoes S_N¹ reaction most readily ? 
(a) (CH₃)₃C—F 
(b) (CH₃)₃C—Cl 
(c) (CH₃)₃C—Br 
(d) (CH₃)₃C—I

Correct Answer is Option ()

(CH₃)₃C-I being a tertiary alkyl halide will most readily undergo S_N¹ reaction.