$P \rightarrow Q$ is a zero order reaction. If the concentration of $P$ decreases from $0.1 \mathrm{M}$ to 0…
$P \rightarrow Q$ 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
$0.05 \mathrm{M}$
$0.025 \mathrm{M}$
$0.02 \mathrm{M}$
$0.01 \mathrm{M}$
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, $P=0.025 \mathrm{M}$