What is the correct relation between rate constant and half-life for a zero order 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 $0.25 \ M$?

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

Which of the following graphs most appropriately represents a zero order reaction?

The rate constant,$k$ of a zero order reaction $2 NH_{3(g)} \xrightarrow[1130 \ K]{Pt} N_{2(g)} + 3 H_{2(g)}$ is $y \times 10^{-4} \ mol \ L^{-1} \ s^{-1}$. The rate of formation of hydrogen (in $mol \ L^{-1} \ s^{-1}$) is

Which graph represents a zero order reaction $[A_{(g)} \to B_{(g)}]$?