Medium INTEGER +4 / -1 PYQ · JEE Mains 2023

The number of incorrect statement/s from the following is ___________

A. The successive half lives of zero order reactions decreases with time.

B. A substance appearing as reactant in the chemical equation may not affect the rate of reaction

C. Order and molecularity of a chemical reaction can be a fractional number

D. The rate constant units of zero and second order reaction are $\mathrm{mol} ~\mathrm{L}^{-1} \mathrm{~s}^{-1}$ and $\mathrm{mol}^{-1} \mathrm{~L} \mathrm{~s}^{-1}$ respectively

Answer (integer) 1

Solution

<p>A. The successive half lives of zero order reactions decreases with time. This statement is <strong>correct</strong>. The half-life of a zero-order reaction is given by the formula $t_{1/2} = [A]_0/2k$, where $[A]_0$ is the initial concentration and k is the rate constant. As the concentration decreases, the half-life also decreases.</p> <p>B. A substance appearing as reactant in the chemical equation may not affect the rate of reaction. This statement is <strong>correct</strong>. For example, in a zero-order reaction, the rate of reaction does not depend on the concentration of reactants.</p> <p>C. Order and molecularity of a chemical reaction can be a fractional number. This statement is <strong>incorrect</strong>. The order of a reaction can be zero, fractional or negative. However, molecularity, which refers to the number of reactant molecules taking part in an elementary reaction, can only be a whole number.</p> <p>D. The rate constant units of zero and second order reaction are $\mathrm{mol} ~\mathrm{L}^{-1} \mathrm{~s}^{-1}$ and $\mathrm{mol}^{-1} \mathrm{~L} \mathrm{~s}^{-1}$ respectively. This statement is <strong>correct</strong>. The units of the rate constant for a zero-order reaction are M/s or mol·L<sup>−1</sup>·s<sup>−1</sup> . The units of the rate constant for a second-order reaction are 1/(M·s) or L·mol<sup>−1</sup>·s<sup>−1 </sup>.</p>

About this question

Subject: Chemistry · Chapter: Chemical Kinetics · Topic: Rate of Reaction

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