Which of the following is a unimolecular reaction?

Write the general reaction,its differential rate equation,and the rate law.

What is the order of reaction if the unit of the rate constant is $s^{-1}$?

The rate constant for the reaction, $2 \,N_2O_{5(g)} \rightarrow 2 \,N_2O_{4(g)} + O_{2(g)}$ is $4.98 \times 10^{-4} \,s^{-1}$. What is the order of the reaction?

Consider the following reaction,
$2H_{2(g)} + 2NO_{(g)} \rightarrow N_{2(g)} + 2H_2O_{(g)}$
which follows the mechanism given below:
$2NO_{(g)} \underset{k_{-1}}{\stackrel{k_1}{\rightleftharpoons}} N_2O_{2(g)}$ (fast equilibrium)
$N_2O_{2(g)} + H_{2(g)} \stackrel{k_2}{\rightarrow} N_2O_{(g)} + H_2O_{(g)}$ (slow reaction)
$N_2O_{(g)} + H_{2(g)} \stackrel{k_3}{\rightarrow} N_{2(g)} + H_2O_{(g)}$ (fast reaction)
The order of the reaction is

For the reaction $A + B \rightarrow$ products,doubling the concentration of $A$ increases the reaction rate by four times,but doubling the concentration of $B$ has no effect on the reaction rate. What is the rate law?