An elementary reaction between $A$ and $B$ is a second order reaction. Which of the following rate equations must be correct?

What is the molecularity of a reaction? Explain its types with examples.

For the reaction $aA \to xP$,the rate is $2.4 \ mMs^{-1}$ when $[A] = 2.2 \ M$. When the concentration of $A$ is halved,the rate becomes $0.6 \ mMs^{-1}$. Determine the order of the reaction with respect to $A$.

The given data are for the reaction:
$2NO_{(g)} + Cl_{2(g)} \to 2NOCl_{(g)}$ at $298 \ K$

Experiment	$[Cl_2] \ (M)$	$[NO] \ (M)$	Rate $(mol \ L^{-1} \sec^{-1})$
$I$	$0.05$	$0.05$	$1 \times 10^{-3}$
$II$	$0.15$	$0.05$	$3 \times 10^{-3}$
$III$	$0.05$	$0.15$	$9 \times 10^{-3}$

The rate law for the reaction is:

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?

The reaction $2 \ NO + Br_2 \rightarrow 2 \ NOBr$ takes place through the mechanism given below:
$NO + Br_2 \Leftrightarrow NOBr_2$ (fast)
$NOBr_2 + NO \rightarrow 2 \ NOBr$ (slow)
The overall order of the reaction is $.....$.