For the equilibrium $\mathrm{A} \rightleftharpoons \mathrm{B}$, the variation of the rate of the forward (a) and reverse (B) reaction with time is given by:

JEE Main · 2020 · 04 Sep 2020 · Shift 1 · Chemical Kinetics

For the equilibrium

A ⇌ B

, the variation of the rate of the forward (a) and reverse (B) reaction with time is given by:

(A)(see structure)
(B)(see structure)
(C)(see structure)
(D)(see structure)
✓ Correct

Answer: (D)

Solution

Starting from pure A, the forward rate is largest at the beginning when

[A]

is high and

[B]

is zero, and it falls as A is consumed, while the reverse rate starts at zero and climbs as

[B]

builds up. The two rates approach each other and, at equilibrium, become equal and then stay constant. The graph in which the forward rate decreases from a high value and the reverse rate rises from zero until they meet and level off together represents this behaviour.

JEE Main · 2020 · 04 Sep 2020 · Shift 1 · Single correct option

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