CBSE 12 Chemistry Question Paper-2021 Term-2 by Pavan | Practice Test to Test Your Knowledge
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  3. CBSE 12 Chemistry Question Paper-2021 Term-2
CBSE 12 Chemistry Question Paper-2021 Term-2

CBSE 12 Chemistry Question Paper-2021 Term-2

This mock test includes actual CBSE Class 12 Chemistry board exam questions from the year 2021 Term-2, helping students understand exam trends and practice real paper format

2025-08-12
Pavan Pavan
CBSE Class 12 Chemistry 2021 Grade 12

Duration

30 min

Questions

30

Marking

Negative

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Questions Preview

Arrange the following in the increasing order of their pKa values: Benzoic acid, Phenol, Picric acid, Salicylic acid.

A
Benzoic acid, Phenol, Salicylic acid, Picric acid
B
Phenol, Benzoic acid, Salicylic acid, Picric acid
C
Picric acid, Benzoic acid, Salicylic acid, Phenol
D
Salicylic acid, Benzoic acid, Picric acid, Phenol

Solutions of two electrolytes ‘A’ and ‘B’ are diluted. The Λm of ‘B’ increases 1.5 times while that of ‘A’ increases 25 times. Which of the two is a strong electrolyte? Justify your answer.

A
Electrolyte A is a strong electrolyte due to a higher increase in Λm.
B
Electrolyte B is a strong electrolyte due to a higher increase in Λm.
C
Both are equally strong electrolytes.
D
Neither is a strong electrolyte.

Give reasons for the following:
a) Presence of Alpha hydrogen in aldehydes and ketones is essential for aldol condensation.
b) 3-Hydroxy pentan-2-one shows a positive Tollen’s test.

A
Alpha hydrogen is essential for aldol condensation because it forms an enolate ion, and 3-Hydroxy pentan-2-one reacts with Tollen’s reagent due to the presence of a reducing group.
B
Alpha hydrogen is not essential for aldol condensation and 3-Hydroxy pentan-2-one does not react with Tollen’s reagent.
C
Alpha hydrogen is essential for aldol condensation and 3-Hydroxy pentan-2-one reacts with Tollen’s reagent due to the presence of a carbonyl group.
D
Neither Alpha hydrogen nor Tollen’s test is relevant in these reactions.

Aniline cannot be prepared by the ammonolysis of chlorobenzene under normal conditions. Why?

A
Because aniline is less reactive than chlorobenzene.
B
Because chlorobenzene is less reactive due to the presence of a strong electron-withdrawing group.
C
Due to the difficulty in the cleavage of the C-Cl bond in chlorobenzene.
D
Aniline is not soluble in water, making the reaction impossible.

Write the formula and hybridization of the following compound: tris(ethane-1,2-diamine) cobalt(III) sulfate.

A
Formula: [Co(C2H8N2)3]SO4; Hybridization: sp3
B
Formula: [Co(C2H8N2)3]SO4; Hybridization: sp2
C
Formula: [Co(C2H8N2)3]SO4; Hybridization: sp3d
D
Formula: [Co(C2H8N2)3]SO4; Hybridization: sp

What happens when an alkene ‘A’ (Mol. formula C5H10) undergoes ozonolysis?

A
The alkene splits into two aldehydes.
B
The alkene gives a mixture of a ketone and an aldehyde.
C
The alkene forms a mixture of two carboxylic acids.
D
The alkene gives a mixture of two alcohols.

Why are fluorides of transition metals more stable in their higher oxidation state compared to lower oxidation states?

A
Because higher oxidation states are stabilized by ligand field splitting.
B
Because transition metals in higher oxidation states have a larger atomic radius.
C
Because fluorides stabilize the higher oxidation state due to their high electronegativity.
D
Because the higher oxidation state is less reactive.

Which one of the following would feel attraction when placed in a magnetic field: Co2+, Ag+, Ti4+, Zn2+?

A
Co2+
B
Ag+
C
Ti4+
D
Zn2+

What happens when N-ethylethanamine reacts with benzenesulphonyl chloride?

A
Formation of an amide.
B
Formation of an ester.
C
Formation of a sulfonamide.
D
Formation of a nitro compound.

Write the IUPAC name for the following organic compound: CH3 – N—CH2CH3

A
N-Methyl ethanamine
B
N-Ethylmethanamine
C
N-Ethylethanamine
D
Methylamine

In the cell with the reaction 2Al(s) + 3Cd2+(0.1M) → 3Cd(s) + 2Al3+(0.01M), what is the value of Ecell if E˚ = 1.260 V?

A
Ecell = 1.260 V
B
Ecell = 1.05 V
C
Ecell = 1.14 V
D
Ecell = 0.9 V

What is the rate of decay of Carbon-14 in an organism if the half-life is 6000 years?

A
The amount of Carbon-14 decreases exponentially.
B
The amount of Carbon-14 remains constant.
C
The amount of Carbon-14 decreases linearly.
D
The amount of Carbon-14 increases.

Why is Ti(IV) more stable than Ti(II) or Ti(III)?

A
Because Ti(IV) has a completely filled d-orbital.
B
Because Ti(IV) has a higher ionization energy.
C
Because Ti(IV) has a lower atomic radius.
D
Because Ti(IV) is the most electronegative form.

Which of the following statements about Zinc is correct?

A
Zinc is a comparatively soft metal, while iron and chromium are typically hard.
B
Zinc is harder than iron and chromium.
C
Zinc and iron have similar hardness.
D
Zinc is a very hard metal, much harder than chromium.

Which process is represented in the figure of an electric field being applied to a liquid?

A
Electrolysis of water
B
Electrolytic refining
C
Electroplating
D
Electrophoresis

What is the application of the process depicted in the figure of electrolysis?

A
Purification of metals
B
Water splitting into hydrogen and oxygen
C
Electroplating of objects
D
DNA separation

Why is an electric field applied in the process shown in the figure?

A
To separate the particles based on charge.
B
To speed up the reactions.
C
To enhance the solubility of solutes.
D
To neutralize the compounds.

What happens when benzylchloride is treated with ammonia followed by the reaction with Chloromethane?

A
Formation of N-benzyl methylamine
B
Formation of N-benzyl formamide
C
Formation of benzylamine
D
Formation of N-benzylacetamide

What happens when aniline reacts with chloroform in the presence of alcoholic potassium hydroxide?

A
Formation of isocyanide
B
Formation of a diazonium salt
C
Formation of aniline hydrochloride
D
Formation of a benzene derivative

Which of the following is true about the transition metal ions in the same series?

A
They show a progressive decrease in radius with increasing atomic number.
B
They show a progressive increase in radius with increasing atomic number.
C
Their ionic radii remain constant throughout the series.
D
Their ionic radii increase initially and then decrease.

What is the IUPAC name for the following organic compound: CH3 – N—CH2CH3?

A
N-Methyl ethanamine
B
N-Ethylethanamine
C
N-Methylethanamine
D
Ethylmethylamine

Why are transition metals with higher oxidation states more stable in their fluorides?

A
Because fluorides have a high electronegativity.
B
Because the transition metals in higher oxidation states form more stable complexes with fluorine.
C
Because fluorides decrease the reactivity of the metals.
D
Because fluorides act as ligands to stabilize the oxidation state.

In a coordination entity, the electronic configuration of the central metal ion is t2g3 eg1. What is the spin state of this complex?

A
The complex is a high-spin complex.
B
The complex is a low-spin complex.
C
The complex is a non-spin complex.
D
The complex has no spin.

What is the crystal field splitting diagram for a d4 transition metal complex?

A
The diagram shows four electrons occupying the lower energy orbitals.
B
The diagram shows two electrons occupying the lower energy orbitals.
C
The diagram shows all five orbitals filled equally.
D
The diagram shows three electrons occupying the lower energy orbitals.

What happens when a transition metal ion like Co2+ is placed in a magnetic field?

A
The ion experiences magnetic attraction due to unpaired electrons.
B
The ion does not experience any magnetic effect.
C
The ion repels the magnetic field.
D
The ion experiences weak magnetic repulsion.

Which of the following metals has the highest melting point in the third transition series?

A
Tungsten
B
Rhodium
C
Platinum
D
Gold

What is the function of pyridine during acylation of aniline?

A
Pyridine acts as a base to neutralize the HCl formed.
B
Pyridine acts as a solvent.
C
Pyridine acts as a catalyst.
D
Pyridine stabilizes the acyl group.

What is the result of the reaction of acetaldehyde with NH2OH?

A
Formation of an oxime
B
Formation of a hydroxy ketone
C
Formation of an enol
D
Formation of an aldehyde hydrate

What is the characteristic test for phenol?

A
Phenol forms a purple complex with ferric chloride.
B
Phenol forms a red complex with ferric chloride.
C
Phenol gives a positive test with bromine water.
D
Phenol reacts with sodium bicarbonate to release CO2.

What is the mechanism for the reaction of ethylamine with chloroethane?

A
Nucleophilic substitution reaction
B
Electrophilic substitution reaction
C
Free radical substitution
D
Elimination reaction