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?

When the initial concentration of the reactant is doubled,the half-life period of a zero order reaction:

Time taken to complete a zero order reaction is . . . . . . .

In the following reaction $A \to B + C,$ the rate constant is $0.001 \ M \ s^{-1}.$ If we start with $1 \ M$ of $A,$ then the concentrations of $A$ and $B$ after $10 \ minutes$ are respectively:

For a reaction $A \rightarrow P$ at $T \text{ K}$, the half-life $(t_{1/2})$ is plotted as a function of initial concentration $[A]_0$ of $A$ as given below. The value of $x$ in the given figure is . . . . . . $\text{s}$ (Nearest integer).

For a zero-order reaction $A \rightarrow \text{Product}$,the half-life is $1 \ h$. If the initial concentration of reactant $A$ is $2.0 \ mol \ L^{-1}$,how many hours will it take for the concentration to decrease from $0.50 \ mol \ L^{-1}$ to $0.25 \ mol \ L^{-1}$?