Chemistry Term 1 2021-2022 Science (English Medium) Class 12 Question Paper Solution

Which one of the following pairs will form an ideal solution?

chloroform and acetone

ethanol and acetone

n-hexane and n-heptane

phenol and aniline

Which of the following is known as amorphous solid?

Glass

Plastic

Rubber

All of the above

The structure of pyrosulphuric acid is

$$\begin{array}{c}\mathrm{O}\phantom{.....}\\ ||\phantom{.....}\\ \mathrm{HO}-\mathrm{S}-\mathrm{O}-\mathrm{OH}\\ ||\phantom{.....}\\ \mathrm{O}\phantom{.....}\end{array}$$

$$\begin{array}{c}\mathrm{O}\\ ||\\ \mathrm{HO}-\mathrm{S}-\mathrm{OH}\\ ||\\ \mathrm{O}\end{array}$$

$$\begin{array}{c}\mathrm{O}\phantom{.......}\mathrm{O}\\ ||\phantom{........}||\\ \mathrm{HO}-\mathrm{S}-\mathrm{O}-\mathrm{S}-\mathrm{OH}\\ ||\phantom{........}||\\ \mathrm{O}\phantom{........}\mathrm{O}\end{array}$$

$$\begin{array}{c}\mathrm{O}\phantom{............}\mathrm{O}\\ ||\phantom{............}||\\ \mathrm{HO}-\mathrm{S}-\mathrm{O}-\mathrm{O}-\mathrm{S}-\mathrm{OH}\\ ||\phantom{............}||\\ \mathrm{O}\phantom{............}\mathrm{O}\end{array}$$

The $$\mathrm{C}-\mathrm{O}-\mathrm{H}$$ bond angle in alcohol is ______.

slightly greater than 109°28'

slightly less than 109°28'

slightly greater than 120°

slightly less than 120°

Consider the following reaction $$\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}=\mathrm{CH}{\phantom{A}}_2\underset{2\cdot \mathrm{aq}\cdot \mathrm{KOH}}{\overset{1\cdot \mathrm{HBr}}{\to }}$$ The major end product is

$$\begin{array}{c}\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}-\mathrm{CH}{\phantom{A}}_3\\ |\phantom{..}\\ \mathrm{OH}\end{array}$$

$$\begin{array}{c}\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}-\mathrm{CH}{\phantom{A}}_3\\ |\phantom{..}\\ \mathrm{Br}\end{array}$$

$$\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}{\phantom{A}}_2-\mathrm{CH}{\phantom{A}}_2-\mathrm{OH}$$

$$\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}{\phantom{A}}_2-\mathrm{CH}{\phantom{A}}_2-\mathrm{Br}$$

Nucleoside are composed of ______.

a pentose sugar and phosphoric acid.

a nitrogenous base and phosphoric acid.

a nitrogenous base and a pentose sugar.

a nitrogenous base, a pentose sugar and phosphoric acid.

The oxidation state −2 is most stable in ______.

O

S

Se

Te

Which of the following is not a characteristic of a crystalline solid?

Definite and characteristic heat of fusion.

Isotropic nature.

A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal.

A true solid.

A regular arrangement of constituent particles.

Sharp melting point.

Which of the following formula represents Raoult's law for a solution containing non-volatile solute?

${\displaystyle {\text{p}}_{\text{solute}}={\text{p}}_{\text{solute}}^{\circ }\cdot {\text{x}}_{\text{solute}}}$

${\displaystyle \text{p}={\text{K}}_{\text{H}}\cdot \text{x}}$

${\displaystyle {\text{p}}_{\text{Total}}={\text{p}}_{\text{solvent}}}$

${\displaystyle {\text{p}}_{\text{solute}}={\text{p}}_{\text{solvent}}^{\circ }\cdot {\text{x}}_{\text{solvent}}}$

An azeotropic solution of two liquids has a boiling point lower than either of the two when it ______.

shows a positive deviation from Raoult's law.

shows a negative deviation from Raoult's law.

shows no deviation from Raoult's law.

is saturated.

Which of the following crystal will show metal excess defect due to extra cation?

$$\mathrm{AgCl}$$

$$\mathrm{NaCl}$$

$$\mathrm{FeO}$$

$$\mathrm{ZnO}$$

Which of the following acids reacts with acetic anhydride to form a compound Aspirin?

Benzoic acid

Salicylic acid

Phthalic acid

Acetic acid

Which of the following statements is wrong?

Oxygen shows pπ-pπ bonding.

Sulphur shows little tendency of catenation.

Oxygen is diatomic whereas sulphur is polyatomic.

$$\mathrm{O}-\mathrm{O}$$ bond is stronger than $$\mathrm{S}-\mathrm{S}$$ bond.

Amino acids which cannot be synthesized in the body and must be obtained through diet are known as ______.

Acidic amino acids

Essential amino acids

Basic amino acids

Non-essential amino acids

Which one of the following halides contains $$\mathrm{C}{\phantom{A}}_{{\text{sp}}^{\text{2-}}}$$ X bond?

Allyl halide

Alkyl halide

Benzyl halide

Vinyl halide

On mixing 20 ml of acetone with 30 ml of chloroform. The total volume of the solution is ______.

< 50 ml

= 50 ml

> 50 ml

= 10 ml

Consider the following compounds:

The correct order of reactivity towards SN² reaction

I > III > II

II > III > I

II > I > III

III > I > II

Which of the following forms strong pπ - pπ bonding?

$$\mathrm{S}{\phantom{A}}_8$$

$$\mathrm{Se}{\phantom{A}}_6$$

$$\mathrm{Te}{\phantom{A}}_4$$

$$\mathrm{O}{\phantom{A}}_2$$

$$\mathrm{F}{\phantom{A}}_2$$ acts as a strong oxidising agent due to ______.

low ${\displaystyle {\Delta }_{\text{bond}}}$H° and low ${\displaystyle {\Delta }_{\text{hyd}}}$H°

low ${\displaystyle {\Delta }_{\text{bond}}}$H° and high ${\displaystyle {\Delta }_{\text{hyd}}}$H°

high ${\displaystyle {\Delta }_{\text{bond}}}$H° and high ${\displaystyle {\Delta }_{\text{eg}}}$H°

low ${\displaystyle {\Delta }_{\text{hyd}}}$H° and low ${\displaystyle {\Delta }_{\text{eg}}}$H°

Which of the following sugar is known as dextrose?

Glucose

Fructose

Ribose

Sucrose

$$\mathrm{Cu}$$ reacts with dilute $$\mathrm{HNO}{\phantom{A}}_3$$ to evolve which gas?

N₂O

NO₂

NO

N₂

Which of the following is a network solid?

SO₂

SiO₂

CO₂

H₂O

Major product formed in the following reaction:

$$\begin{array}{c}\mathrm{CH}{\phantom{A}}_3\phantom{.............}\\ |\phantom{...............}\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{Br}+\mathrm{NaOCH}{\phantom{A}}_3⟶\\ |\phantom{...............}\\ \mathrm{CH}{\phantom{A}}_3\phantom{.............}\end{array}$$

$$\begin{array}{c}\phantom{...}\mathrm{CH}{\phantom{A}}_3\\ |\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{ONa}\\ |\\ \phantom{...}\mathrm{CH}{\phantom{A}}_3\end{array}$$

$$\begin{array}{c}\phantom{.}\mathrm{CH}{\phantom{A}}_3\\ |\phantom{..}\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{OCH}{\phantom{A}}_3\\ |\phantom{..}\\ \phantom{.}\mathrm{CH}{\phantom{A}}_3\end{array}$$

$$\begin{array}{c}\phantom{...}\mathrm{CH}{\phantom{A}}_3\phantom{......}\mathrm{CH}{\phantom{A}}_3\\ |\phantom{.........}|\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{O}-\mathrm{C}-\mathrm{CH}{\phantom{A}}_3\\ |\phantom{.........}|\\ \phantom{...}\mathrm{CH}{\phantom{A}}_3\phantom{......}\mathrm{CH}{\phantom{A}}_3\end{array}$$

$$\begin{array}{c}\phantom{...}\mathrm{CH}{\phantom{A}}_3\\ |\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}=\mathrm{CH}{\phantom{A}}_2\end{array}$$

Chlorine reacts with cold and dilute $$\mathrm{NaOH}$$ to give:

NaCl and NaClO₃

NaCl and NaClO

NaCl and NaClO₄

NaClO and NaClO₃

Elevation of boiling point is inversely proportional to ______.

molal elevation constant (K_b)

molality (m)

molar mass of solute (M)

weight of solute (W)

An unknown gas 'X' is dissolved in water at 2.5 bar pressure and has mole fraction 0.04 in solution. The mole fraction of 'X' gas when the pressure of gas is doubled at the same temperature is ______.

0.08

0.04

0.02

0.92

The base which is present in DNA but not in RNA.

Cytosine

Guanine

Adenine

Thymine

In the following reaction $$\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}{\phantom{A}}_2\mathrm{OH}\stackrel{\mathrm{PCC}}{\to }$$ the product formed is ______.

CH₃ − CHO and CH₃CH₂OH

CH₃ − CH = CH − COOH

CH₃ − CH = CH − CHO

CH₃ − CH₂ − CH₂ − CHO

Enantiomers differ only in ______.

boiling point

rotation of polarized light

melting point

solubility

The number of lone pairs of electrons in $$\mathrm{XeF}{\phantom{A}}_4$$ is ______.

zero

one

two

three

Sulphuric acid is used to prepare more volatile acids from their corresponding salts due to its ______.

strong acidic nature

low volatility

strong affinity for water

ability to act as a dehydrating agent

An element with density 6 g cm⁻³ forms a fcc lattice with edge length of 4 × 10⁻⁸ cm. The molar mass of the element is ______.

(N_A = 6 × 10²³ mol⁻¹)

57.6 g mol⁻¹

28.8 g mol⁻¹

82.6 g mol⁻¹

62 g mol⁻¹

In the reaction

compound 'Y' is

Which of the following is the weakest reducing agent in group 15?

$$\mathrm{NH}{\phantom{A}}_3$$

$$\mathrm{PH}{\phantom{A}}_3$$

$$\mathrm{AsH}{\phantom{A}}_3$$

$$\mathrm{BiH}{\phantom{A}}_3$$

The boiling point of a 0.2 m solution of a non-electrolyte in water is ______.

(K_b, for water = 0.52 K kg mol⁻¹)

100°C

100.52°C

100.104°C

l00.26°C

Nucleic acids are polymer of ______.

amino acids

nucleosides

nucleotides

glucose

Which of the following gas dimerises to become stable?

$$\mathrm{CO}{\phantom{A}}_2{\phantom{A}}_{(\mathrm{g})}$$

$$\mathrm{NO}{\phantom{A}}_2{\phantom{A}}_{(\mathrm{g})}$$

$$\mathrm{SO}{\phantom{A}}_2{\phantom{A}}_{(\mathrm{g})}$$

$$\mathrm{N}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_{(\mathrm{g})}$$

In the following diagram point, 'X' represents

Boiling point of solution

Freezing point of solvent

Boiling point of solvent

Freezing point of solution

XeF₆ on reaction with NaF gives ______.

Na⁺[XeF₇]^-

[NaF₂]^-[XeF₅]⁺]

Na⁺[XeF₆]^-

[NaF₂]⁺[XeF₅]^-

Glucose on reaction with $$\mathrm{Br}{\phantom{A}}_2$$ water gives ______.

Saccharic acid

Hexanoic acid

Gluconic acid

Salicylic acid

Which of the following is optically inactive?

(+)−Butan-2-ol

(−)−Butan-2-ol

(±)−Butan-2-ol

(+)−2-Bromobutane

Which of the following is not a correct statement?

Halogens are strong oxidising agents.

Halogens are more reactive than interhalogens.

All halogens are coloured.

Halogens have maximum negative electron gain enthalpy.

Which of the following has highest boiling point?

C₂H₅ − F

C₂H₅ − Cl

C₂H₅ − Br

C₂H₅ − I

Which of the following isomer of pentane C₅H₁₂ will give three isomeric monochlorides on photochemical chlorination?

$$\begin{array}{c}\phantom{...}\mathrm{CH}{\phantom{A}}_3\\ |\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{CH}{\phantom{A}}_3\\ |\\ \phantom{...}\mathrm{CH}{\phantom{A}}_3\end{array}$$

CH₃CH₂CH₂CH₂CH₃

$$\begin{array}{c}\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}-\mathrm{CH}{\phantom{A}}_2-\mathrm{CH}{\phantom{A}}_3\\ |\phantom{.........}\\ \mathrm{CH}{\phantom{A}}_3\phantom{......}\end{array}$$

All of the above

Assertion (A): A raw mango placed in a saline solution loses water and shrivel into pickle.

Reason (R): Through the process of reverse osmosis, raw mango shrivel into pickle.

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

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

A is true but R is false.

A is false but R is true.

Assertion (A): H₂S is less acidic than H₂Te.

Reason (R): H-S bond has more Δ_bond H° than H-Te bond.

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

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

A is true but R is false.

A is false but R is true.

Assertion (A): Chlorobenzene is less reactive towards nucleophilic substitution reaction.

Reason (R): Nitro group in chlorobenzene increases its reactivity towards nucleophilic substitution reaction.

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

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

A is true but R is false.

A is false but R is true.

Assertion (A): Due to schottky defect, there is no effect on the density of a solid.

Reason (R): Equal number of cations and anions are missing from their normal sites in Schottky defect.

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

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

A is true but R is false.

A is false but R is true.

Assertion (A): Fluorine forms only one oxoacid HOF.

Reason (R): Fluorine atom is highly electronegative.

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

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

A is true but R is false.

A is false but R is true.

Match the following:

Which of the following is the best matched options?

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

(i) - (c), (ii) - (a), (iii) - (d), (v) - (b)

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

(i) - (a), (ii) - (b), (v) - (c), (iv) - (d)

Which of the following analogies is correct?

XeF₂ : linear :: XeF₆ : square planar

moist SO₂ : Reducing agent :: Cl₂ : bleaching agent

N₂ : Highly reactive gas :: F₂ : inert at room temperature

NH₃ : strong base :: HI : weak acid

Complete the following analogy:

Curdling of milk : A :: α-helix : B

A: Primary structure
B: Secondary structure

A: Denatured protein
B: Primary structure

A: Secondary structure
B: Denatured protein

A: Denatured protein
B: Secondary structure

Read the passage given below and answer the following question:

Which of the following alcohols is resistant to oxidation?

$$\begin{array}{c}\phantom{...}\mathrm{CH}{\phantom{A}}_3\\ \phantom{.}|\\ \mathrm{CH}{\phantom{A}}_3-\mathrm{C}-\mathrm{OH}\\ \phantom{.}|\\ \phantom{...}\mathrm{CH}{\phantom{A}}_3\end{array}$$

$$\begin{array}{c}\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}-\mathrm{OH}\\ |\phantom{.}\\ \phantom{..}\mathrm{CH}{\phantom{A}}_3\end{array}$$

$$\mathrm{CH}{\phantom{A}}_3-\mathrm{CH}{\phantom{A}}_2-\mathrm{OH}$$

$$\mathrm{CH}{\phantom{A}}_3-\mathrm{OH}$$

Read the passage given below and answer the following question:

Which of the following group increases the acidic character of phenol?

CH₃O^-

$$\mathrm{CH}{\phantom{A}}_3^{-}$$

$$\mathrm{NO}{\phantom{A}}_2^{-}$$

All of these

Read the passage given below and answer the following question:

Consider the following reaction:

the products X and Y are