Q26 / 160 · AP EAMCET 2022 (08 Jul Shift 2) · Chemistry

$P \rightarrow Q$ is a zero order reaction. If the concentration of $P$ decreases from $0.1 \mathrm{M}$ to 0.05 in 10 seconds, the concentration of $P$ after 15 seconds time is

  • A
    $0.05 \mathrm{M}$
  • Correct answer
    B
    $0.025 \mathrm{M}$
  • C
    $0.02 \mathrm{M}$
  • D
    $0.01 \mathrm{M}$

Solution

Given that, $P \rightarrow Q$ is a zero order reaction. Initial concentration, $[A]_0=0.1 \mathrm{M}$ Final concentration, $[A]_t=0.05 \mathrm{M}$ Time taken, $t=10 \mathrm{~s}$ For, zero order reaction, $k=\frac{[A]_0-[A]_t}{t}$ $=\frac{0.1-0.05}{10}=0.005 \mathrm{M} \mathrm{s}^{-1}$ Now, for concentration of $P$ after 15 seconds, $0.005=\frac{[0.05]-P}{15}$ On solving we will get, $P=0.025 \mathrm{M}$

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

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