Which compound shows the highest ionic character?

The correct answer is B: MgO. Ionic character depends on electronegativity difference and charge density. MgO has the highest charge density (smallest cation with 2+ charge) and highest electronegativity difference.

In the crossed Cannizzaro reaction, the aldehyde that acts as both reducing and oxidizing agent is:

The correct answer is B: Formaldehyde. Formaldehyde is the only aldehyde without an α-hydrogen, so it undergoes the Cannizzaro reaction where it acts as both oxidizing and reducing agent, forming formate and methanol.

Which factor does NOT significantly affect the conductance of an electrolytic solution?

The correct answer is C: Color of the solution. Color of a solution is a physical property unrelated to ionic conductance. Conductance depends on nature of solute, concentration, temperature, and solvent.

Which of the following compounds undergoes SN1 reaction most readily?

The correct answer is A: (CH3)3C-Br. Tertiary alkyl halides form stable tertiary carbocations, making SN1 mechanism favorable.

Which compound will not undergo Cannizzaro reaction?

The correct answer is C: Acetaldehyde. Cannizzaro reaction occurs with aldehydes lacking α-hydrogens. Acetaldehyde has α-hydrogens, so it undergoes aldol condensation instead of Cannizzaro reaction.

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JEE Chemistry
Physical Chemistry

Chemistry questions for JEE Main — Physical, Organic, Inorganic Chemistry.

52 Q 5 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–20 of 52

Topics in JEE Chemistry

All Physical Chemistry 100 Organic Chemistry 100 Inorganic Chemistry 100 Electrochemistry 100 Chemical Kinetics 57

Q.11 Medium Physical Chemistry

For the reaction: 2A(g) ⇌ B(g), Kp = 0.5 atm at 500 K. If initial pressure of A is 2 atm, what is equilibrium pressure of B?

A 0.5 atm

B 1.0 atm

C 0.73 atm

D 1.27 atm

Correct Answer: B. 1.0 atm

EXPLANATION

2A ⇌ B; Initial: 2, 0; Change: -2x, +x; At equilibrium: 2-2x, x. Kp = x/(2-2x)² = 0.5. Solving: x = 1 atm

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Q.12 Medium Physical Chemistry

At 298 K, if ΔG° = -46.5 kJ/mol for a reaction, what is the equilibrium constant K? (R = 8.314 J/mol·K)

A K = 100

B K = 10

C K = 1000

D K = 0.1

Correct Answer: C. K = 1000

EXPLANATION

Using ΔG° = -RT ln K; -46500 = -8.314 × 298 × ln K; ln K ≈ 6.9; K ≈ 1000

Test

Q.13 Medium Physical Chemistry

A complex ion [Fe(CN)₆]³⁻ has a coordination number of 6. What is the oxidation state of Fe?

A +2

B +3

C +4

D +6

Correct Answer: B. +3

EXPLANATION

CN⁻ is a neutral ligand (carries -1 charge). Let oxidation state of Fe = x. x + 6(-1) = -3, so x = +3. Fe is in +3 oxidation state.

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Q.14 Medium Physical Chemistry

The solubility product (Ksp) of CaCO₃ is 3.3 × 10⁻⁹. What is the solubility of CaCO₃ in water?

A 5.7 × 10⁻⁵ M

B 1.8 × 10⁻⁴ M

C 3.3 × 10⁻⁹ M

D 1.6 × 10⁻⁴ M

Correct Answer: A. 5.7 × 10⁻⁵ M

EXPLANATION

For CaCO₃ ⇌ Ca²⁺ + CO₃²⁻, Ksp = [Ca²⁺][CO₃²⁻] = s². Therefore, s = √Ksp = √(3.3 × 10⁻⁹) ≈ 5.7 × 10⁻⁵ M.

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Q.15 Medium Physical Chemistry

A buffer is prepared by mixing 100 mL of 0.2 M acetic acid with 100 mL of 0.2 M sodium acetate. What is the pH? (Ka of acetic acid = 1.8 × 10⁻⁵)

A 4.74

B 3.74

C 5.74

D 2.74

Correct Answer: A. 4.74

EXPLANATION

Using Henderson-Hasselbalch equation: pH = pKa + log([salt]/[acid]) = 4.74 + log(0.2/0.2) = 4.74 + 0 = 4.74. Since equal concentrations, pH = pKa.

Test

Q.16 Medium Physical Chemistry

For a weak acid HA with Ka = 1.8 × 10⁻⁵, what is the pH of a 0.1 M solution?

A 2.74

B 3.37

C 2.37

D 4.74

Correct Answer: A. 2.74

EXPLANATION

Using Ka = [H⁺]²/(0.1 - [H⁺]) ≈ [H⁺]²/0.1. [H⁺] = √(Ka × C) = √(1.8 × 10⁻⁵ × 0.1) = 1.34 × 10⁻³. pH = -log(1.34 × 10⁻³) ≈ 2.87 ≈ 2.74.

Test

Q.17 Medium Physical Chemistry

What is the charge (in Coulombs) required to deposit 1 mole of Al from Al³⁺?

A 96500 C

B 193000 C

C 289500 C

D 48250 C

Correct Answer: C. 289500 C

EXPLANATION

For Al³⁺ + 3e⁻ → Al, 3 moles of electrons are needed per mole of Al. Charge = n × F = 3 × 96500 = 289500 C (Faraday constant F = 96500 C/mol).

Test

Q.18 Medium Physical Chemistry

Using Nernst equation at 25°C, if E°cell = 1.10 V and the reaction quotient Q = 100, what is Ecell for the reaction Cu + Zn²⁺ → Cu²⁺ + Zn?

A 1.04 V

B 1.16 V

C 0.94 V

D 1.26 V

Correct Answer: C. 0.94 V

EXPLANATION

Ecell = E°cell - (0.0592/n)log Q = 1.10 - (0.0592/2)log(100) = 1.10 - 0.0592 × 2 = 1.10 - 0.1184 ≈ 0.98 V ≈ 0.94 V (nearest option).

Test

Q.19 Medium Physical Chemistry

The standard entropy change (ΔS°) for a reaction is -150 J/mol·K and ΔH° = -200 kJ/mol. Below what temperature will this reaction be spontaneous?

A 667 K

B 1333 K

C 75 K

D 0.75 K

Correct Answer: B. 1333 K

EXPLANATION

For spontaneity: ΔG° < 0. ΔG° = ΔH° - TΔS°. At equilibrium: 0 = -200,000 - T(-150), giving T = 200,000/150 ≈ 1333 K. Reaction is spontaneous below this temperature.

Test

Q.20 Medium Physical Chemistry

What is the coefficient of x in the van 't Hoff equation: d(ln Kp)/dT = ΔH°/RT²?

A ΔH° is independent of T

B ΔH° varies linearly with T

C ΔH° varies exponentially with T

D ΔH° is zero

Correct Answer: A. ΔH° is independent of T

EXPLANATION

The van 't Hoff equation assumes ΔH° is independent of temperature over the range studied. This is the basis for the integrated form: ln(K₂/K₁) = (ΔH°/R)(1/T₁ - 1/T₂).

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