For the reaction $A \rightarrow B$,the following graph was obtained. The time required (in seconds) for the concentration of $A$ to reduce to $2.5 \ g \ L^{-1}$ (if the initial concentration of $A$ was $50 \ g \ L^{-1}$) is $........$ (Nearest integer). Given: $\log 2 = 0.3010$.

In a first order reaction,the concentration of the reactant is reduced to $25\%$ in one hour. The half-life period of the reaction is: (in $hr$)

Give examples of first-order reactions.

In the reaction $2N_2O_5 \to 4NO_2 + O_2$,the initial pressure is $500 \ atm$ and the rate constant $K$ is $3.38 \times 10^{-5} \ s^{-1}$. After $10 \ minutes$,the final pressure of $N_2O_5$ is ........ $atm$.

$PCl_{5(g)} \rightarrow PCl_{3(g)} + Cl_{2(g)}$
In the above first order reaction,the concentration of $PCl_{5}$ reduces from an initial concentration of $50 \ mol \ L^{-1}$ to $10 \ mol \ L^{-1}$ in $120 \ minutes$ at $300 \ K$. The rate constant for the reaction at $300 \ K$ is $X \times 10^{-2} \ min^{-1}$. The value of $X$ is $......$
$[$ Given $\log 5 = 0.6989 ]$

The first order reaction takes $20 \ min$ to complete $15\%$. How much time is required to complete $75\%$ of the reaction (in $min$)?