In the reduction of ketones and aldehydes using DIBAL-H, the product is:

The correct answer is B: An alcohol. DIBAL-H (Diisobutylaluminum hydride) reduces carbonyl compounds to primary alcohols (from aldehydes) or secondary alcohols (from ketones). It's milder than LiAlH4.

The reduction potential of Fe³⁺/Fe²⁺ is +0.77 V. This indicates:

The correct answer is C: Both A and B. Positive E° means Fe³⁺ is easily reduced and Fe²⁺ is easily oxidized. Fe³⁺ is a strong oxidizing agent relative to Fe²⁺.

Which statement about diagonal relationship in periodic table is correct?

The correct answer is C: Be shows diagonal relationship with Al. Be and Al show diagonal relationship due to similar charge-to-radius ratio. Both form covalent compounds and amphoteric oxides.

In electrochemistry, overpotential is important because:

The correct answer is B: It is the excess potential required beyond E° to drive an electrode reaction at appreciable rates. Overpotential (η) is the excess potential needed to overcome kinetic barriers and drive the reaction at significant rates. It depends on current density and the nature of the electrode.

Which of the following graphs represents a first-order reaction?

The correct answer is B: Plot of ln[A] vs t is linear. For a first-order reaction, ln[A] = ln[A]₀ - kt, so a plot of ln[A] vs t gives a straight line with slope -k.

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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 51–52 of 52

Topics in JEE Chemistry

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

Q.51 Medium Physical Chemistry

The rate constant of a reaction at 25°C is k₁ and at 75°C is k₂. If Ea = 60 kJ/mol, what is k₂/k₁? (R = 8.314 J/mol·K)

A 10.3

B 25.8

C 103

D 258

Correct Answer: C. 103

EXPLANATION

Using Arrhenius equation: ln(k₂/k₁) = (Ea/R)(1/T₁ - 1/T₂) = (60000/8.314)(1/298 - 1/348) ≈ 4.63, so k₂/k₁ ≈ 103.

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Q.52 Medium Physical Chemistry

At critical point, the compressibility factor Z equals:

A 1

B 0.5

C 0.27

D 2

Correct Answer: C. 0.27

EXPLANATION

At the critical point, Z = PcVc/RTc = 0.27 for most real gases (theoretical value for van der Waals gas).

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