Which statement is correct regarding a zero order reaction?

The rate constant of a zero order reaction is $2.0 \times 10^{-2} \ mol \ L^{-1} \ s^{-1}$. If the concentration of the reactant after $25 \ s$ is $0.5 \ M$,then find the initial concentration of the reactant. (in $M$)

What is the value of the slope of a graph obtained by plotting the concentration of reactant $[A]_t$ versus time for a zero order reaction?

For a reaction,doubling the concentration of the reactant doubles the half-life period. What is the order of the reaction?

The rate equation for a reaction $A \rightarrow B$ is $r=k[A]^{0}$. If the initial concentration of the reactant is $a \ mol \ dm^{-3}$,the half-life period of the reaction is

For a general reaction $A \to B$,a plot of the concentration of $A$ versus time is given in the figure. Answer the following questions based on this graph:
$(i)$ What is the order of the reaction?
$(ii)$ What is the slope of the curve?
$(iii)$ What are the units of the rate constant?