What is the correct relation between rate constant and half-life for a zero order reaction?

The unit of velocity constant in case of zero order reaction is

In which one of the following reactions,the rate constant has the unit $mol \ L^{-1} \ s^{-1}$?

$A$ zero order reaction is one whose rate is independent of

$A \rightarrow P$ is a zero order reaction. At $298 \ K$ the rate constant of the reaction is $1 \times 10^{-3} \ mol \ L^{-1} \ s^{-1}$. Initial concentration of '$A$' is $0.1 \ mol \ L^{-1}$. What is the concentration of '$A$' after $10 \ s$?

For a zero-order reaction,the correct expression for rate constant $(k)$ at half-life time $(t_{1/2})$ is ($[R_0] =$ initial concentration of reactant).