Q5 / 150 · MHT CET 2024 (10 May Shift 1) · Chemistry

For a zero order reaction, $\mathrm{A} \longrightarrow$ product, concentration of A decreases from $1.2 \mathrm{moldm}^{-3}$ to $0.4 \mathrm{moldm}^{-3}$ in 240 second. What is rate constant of the reaction?

  • A
    $0.1 \mathrm{~mol} \mathrm{dm}^{-3}$ minute ${ }^{-1}$
  • Correct answer
    B
    $0.2 \mathrm{~mol} \mathrm{dm}^{-3}$ minute $^{-1}$
  • C
    $0.3 \mathrm{~mol} \mathrm{dm}^{-3}$ minute ${ }^{-1}$
  • D
    $0.4 \mathrm{~mol} \mathrm{dm}^{-3}$ minute $^{-1}$

Solution

For a zero order reaction, $\begin{aligned} \mathrm{k} & =\frac{[\mathrm{A}]_0-[\mathrm{A}]_{\mathrm{t}}}{\mathrm{t}} \\ & =\frac{(1.2-0.4) \text { moldm }^{-3}}{4 \text { minute }(\because 1 \text { minute }=60 \text { second })} \\ & =0.2 \mathrm{~mol} \mathrm{dm}^{-3} \text { minute }^{-1}\end{aligned}$

Hence, the correct answer is option: 'B'.

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