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Chemistry · PYQ NEET UG 2026
हिन्दी$2\text{A} \xrightarrow{k} \text{B}$ is a zero-order reaction, where $k = 1.0\text{ mol L}^{-1}\text{ min}^{-1}$. If the initial concentration of A is $2\text{ M}$, then the time taken to complete $75\%$ of the reaction will be
Correct answer · Option 2
$0.75\text{ min}$
Explanation
For reaction $2\text{A} \rightarrow \text{B}$, rate $= -\frac{1}{2}\frac{d[A]}{dt} = k \implies \frac{d[A]}{dt} = -2k$. Thus for zero-order with stoichiometric coefficient, $[A]_0 - [A]_t = 2kt$. For $75\%$ completion, reacted amount $= 0.75 [A]_0 = 0.75 \times 2 = 1.5\text{ M}$. Therefore $1.5 = 2(1.0)t \implies t = 0.75\text{ min}$.
