Chemical Kinetics Important MCQs for NEET 2026

Chemical Kinetics – Important MCQs (NEET 2026)

The slope of Arrhenius plot (ln k v/s 1/T) of first order reaction is −5 × 10³ K. The value of E_a of the reaction is. Choose the correct option for your answer. [Given R = 8.314 J K⁻¹ mol⁻¹]

−83 kJ mol⁻¹

41.5 kJ mol⁻¹

83.0 kJ mol⁻¹

166 kJ mol⁻¹

For the chemical reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g) the correct option is :

− d[N₂]/dt = 2 d[NH₃]/dt

− d[N₂]/dt = 1/2 d[NH₃]/dt

3 d[H₂]/dt = 2 d[NH₃]/dt

− 1/3 d[H₂]/dt = − 1/2 d[NH₃]/dt

If the rate constant of a reaction is 0.03 s⁻¹, how much time does it take for 7.2 mol L⁻¹ concentration of the reactant to get reduced to 0.9 mol L⁻¹? (Given: log 2 = 0.301)

210 s

21.0 s

69.3 s

23.1 s

If the half-life (t_1/2) for a first order reaction is 1 minute, then the time required for 99.9% completion of the reaction is closest to :

5 minutes

10 minutes

2 minutes

4 minutes

For the reaction, N₂ + 3H₂ → 2NH₃, if d[NH₃]/dt = 2 × 10⁻⁴ mol L⁻¹ s⁻¹, the value of − d[H₂]/dt would be

4 × 10⁻⁴ mol L⁻¹ s⁻¹

6 × 10⁻⁴ mol L⁻¹ s⁻¹

1 × 10⁻⁴ mol L⁻¹ s⁻¹

3 × 10⁻⁴ mol L⁻¹ s⁻¹

The unit of rate constant for a zero order reaction is

mol L⁻¹ s⁻¹

L mol⁻¹ s⁻¹

L² mol⁻² s⁻¹

s⁻¹

The activation energy for a simple chemical reaction A ⇌ B is E_a in forward direction. The activation energy for reverse reaction

is negative of E_a

is always less than E_a

can be less than or more than E_a

is always double of E_a

The decomposition of phosphine (PH₃) on tungsten at low pressure is a first-order reaction. It is because the

rate is proportional to the surface coverage

rate is inversely proportional to the surface coverage

rate is independent of the surface coverage

rate of decomposition is very slow

For the reaction, 2A + B → 3C + D, which of the following does not express the reaction rate?

− d[A]/2dt

− d[C]/3dt

− d[B]/dt

d[D]/dt

What is the activation energy for a reaction if its rate doubles when the temperature is raised from 20°C to 35°C? (R = 8.314 J mol⁻¹ K⁻¹)

34.7 kJ mol⁻¹

15.1 kJ mol⁻¹

342 kJ mol⁻¹

269 kJ mol⁻¹