What is the molecularity of the following reaction ?

$1.$ $NH _{4} NO _{2( s )} \rightarrow N _{2( g )}+2 H _{2} O$

$2.$ $2 HI \rightarrow H _{2}+ I _{2}$

$3.$ $2 NO + O _{2} \rightarrow 2 NO _{2}$

The conversion of $A \to B$ follows second order kinetics. Doubling the concentration of $A$ will increase the rate of formation of $B$ by a factor

The rate of the reaction becomes twice when the concentration of reactant becomes $8$ times then the order of the reaction is

For a reaction $2NO(g) + C{l_2}(g)$ $\rightleftharpoons$ $\,2NOCl(g)$. When concentration of $C{l_2}$ is doubled, the rate of reaction becomes two times of the original. When the concentration of $NO$  is doubled the rate becomes four times. What is the order of the reaction

For the reaction taking place on water, the order of reaction is

${{H}_{2}}+C{{l}_{2}}\xrightarrow{\text{Sunlight}}2HCl$

The following results have been obtained during the kinetic studies of the reaction:

$2 A+B \rightarrow C+D$

Determine the rate law and the rate constant for the reaction.