Q25 / 90 · JEE Main 2021 (25 Jul Shift 2) · Chemistry

For a chemical reaction $A \to B$ , it was found that concentration of $B$ is increased by $0.2 mol L^{- 1}$ in 30 min. The average rate of the reaction is ________ $\times 10^{- 1} mol L^{- 1} h^{- 1}$ . (in nearest integer)

Correct answer: 4

Solution

$A ⟶ B$

$t = 0 0$

$t = 30 \min 0.2 M$

Av. rate of reaction $= - \frac{Δ [A]}{Δ t} = \frac{Δ [B]}{Δ t} = \frac{(0.2 - 0)}{\frac{1}{2}}$

$= 0.4 = 4 \times 10^{- 1} mol / L \times hr$

Hence, the correct answer is 4.