The unit of rate constant for a zero order reaction is

What is the concentration (in $mol \ L^{-1}$) of the product $B$ after $20 \ s$ in the following reaction? Given that $A \longrightarrow 3B$,rate $= k[A]^0$. The data is provided in the table below:
| Time $(s)$ | Concentration of reactant $A$ $(mol \ L^{-1})$ |
| :--- | :--- |
| $0$ | $0.1$ |
| $15$ | $0.05$ |
| $20$ | $0.1 - x$ |

For the reaction $A \rightarrow \text{products}$,the graph of $t_{1/2}$ versus $[A]_0$ is given below. The concentration of $A$ at $10 \ \text{minutes}$ is $.......... \times 10^{-3} \ \text{mol L}^{-1}$ $(nearest \ integer)$. The reaction was started with $2.5 \ \text{mol L}^{-1}$ of $A$.

Consider the reaction $aX \to bY$, for which the rate constant at $30^\circ C$ is $1 \times 10^{-3} \text{ mol L}^{-1} \text{ s}^{-1}$. Which of the following statements are true?
$A$. When concentration of $X$ is increased to four times, the rate of reaction becomes $16$ times.
$B$. The reaction is a second order reaction.
$C$. The half-life period is independent of the concentration of $X$.
$D$. Decomposition of $N_2O_5$ is an example of the above reaction.
$E$. $\ln \frac{[R]_0}{[R]}$ vs time is valid for the above reaction.

For a reaction $A \rightarrow$ products,the half-life period is $1 \ h$. The initial concentration of reactant $A$ is $2 \ M$. If this reaction is of zero order,how many hours will it take for the concentration of the reactant to decrease from $0.5 \ M$ to $0.25 \ M$?