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NEET UG MCQ questions — Physics, Chemistry, Botany & Zoology for medical entrance.

453 Q 4 Subjects 12th (PCB)

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Difficulty: All Easy Medium Hard 11–20 of 453

Subjects in NEET UG

All NEET Physics 0 NEET Chemistry 88 NEET Botany 276 NEET Zoology 540

Q.11 Medium NEET Chemistry Physical Chemistry

At 25°C, for the reaction: Cu²⁺(aq) + Zn(s) → Cu(s) + Zn²⁺(aq), E° = 1.1 V. What is ΔG°? (F = 96500 C/mol)

A -212.3 kJ/mol

B -106.15 kJ/mol

C -424.6 kJ/mol

D -53.075 kJ/mol

Correct Answer: A. -212.3 kJ/mol

EXPLANATION

ΔG° = -nFE° = -2 × 96500 × 1.1 = -212300 J/mol = -212.3 kJ/mol

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Q.12 Medium NEET Chemistry Physical Chemistry

In a galvanic cell, at the cathode:

A Oxidation occurs and it's the positive electrode

B Reduction occurs and it's the negative electrode

C Reduction occurs and it's the positive electrode

D Oxidation occurs and it's the negative electrode

Correct Answer: C. Reduction occurs and it's the positive electrode

EXPLANATION

Cathode is where reduction occurs. It's the positive electrode in a galvanic cell as it attracts cations.

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Q.13 Medium NEET Chemistry Physical Chemistry

A buffer solution is prepared by mixing 100 mL of 0.1 M CH₃COOH and 100 mL of 0.1 M CH₃COONa. The pKa of acetic acid is 4.74. What is the pH?

A 3.74

B 4.74

C 5.74

D 6.74

Correct Answer: B. 4.74

EXPLANATION

Using Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]) = 4.74 + log(0.1/0.1) = 4.74

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Q.14 Medium NEET Chemistry Physical Chemistry

For the exothermic reaction: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), increasing temperature will:

A Increase Kc and shift equilibrium right

B Decrease Kc and shift equilibrium left

C Increase Kc and shift equilibrium left

D No effect on equilibrium

Correct Answer: B. Decrease Kc and shift equilibrium left

EXPLANATION

For exothermic reactions, increasing temperature decreases Kc (unfavorable) and shifts equilibrium left (Le Chatelier's principle).

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Q.15 Medium NEET Chemistry Physical Chemistry

The osmotic pressure of a solution is given by π = iMRT. If 0.1 M glucose solution has osmotic pressure 2.46 atm at 273 K, what is the van't Hoff factor?

A 0.5

B 1

C 2

D 4

Correct Answer: B. 1

EXPLANATION

i = π/(MRT) = 2.46/(0.1 × 0.0821 × 273) ≈ 1. Glucose is non-electrolyte with i = 1

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Q.16 Medium NEET Chemistry Physical Chemistry

A buffer solution contains 0.1 M acetic acid and 0.1 M sodium acetate. If Ka = 1.8 × 10⁻⁵, calculate the pH:

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(0.1/0.1) = 4.74 + 0 = 4.74.

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Q.17 Medium NEET Chemistry Physical Chemistry

What is the entropy change when 18 g of ice at 273 K is converted to water at 273 K? (ΔfusH = 6 kJ/mol)

A 22.0 J/K

B 11.0 J/K

C 44.0 J/K

D 5.5 J/K

Correct Answer: A. 22.0 J/K

EXPLANATION

ΔS = ΔH/T = (6000 J/mol) / 273 K = 22.0 J/(mol·K). For 18 g (1 mole) of ice, ΔS = 22.0 J/K.

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Q.18 Medium NEET Chemistry Physical Chemistry

For the reaction: A → B, if the order is 2 and rate constant k = 0.5 L·mol⁻¹·s⁻¹, find the half-life when initial concentration is 2 M.

A 1.0 s

B 2.0 s

C 0.5 s

D 4.0 s

Correct Answer: A. 1.0 s

EXPLANATION

For second-order reactions, t₁/₂ = 1/(k[A₀]) = 1/(0.5 × 2) = 1.0 s.

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Q.19 Medium NEET Chemistry Physical Chemistry

The standard cell potential for a cell is E° = 1.10 V. Calculate ΔG° (F = 96500 C/mol, n = 2):

A -212.3 kJ/mol

B +212.3 kJ/mol

C -106.15 kJ/mol

D +106.15 kJ/mol

Correct Answer: A. -212.3 kJ/mol

EXPLANATION

ΔG° = -nFE° = -2 × 96500 × 1.10 = -212,300 J/mol = -212.3 kJ/mol.

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Q.20 Medium NEET Chemistry Physical Chemistry

For a reversible adiabatic process of an ideal gas, which statement is correct?

A ΔS = 0 (entropy is constant)

B ΔU = 0

C q = 0 and ΔS > 0

D ΔH = 0

Correct Answer: A. ΔS = 0 (entropy is constant)

EXPLANATION

For a reversible adiabatic process, q = 0 and ΔS = 0 because there is no heat exchange and the process is reversible, making it isentropic.

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Questions 453

Subjects 4

Eligibility 12th (PCB)

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