Which of the following is an elementary reaction?

For the reaction $X_{2(g)} + Y_{2(g)} \rightarrow 2XY_{(g)}$,the following data are observed:

$[X_{2}] \ (M)$	$[Y_{2}] \ (M)$	Rate of appearance of $XY \ (M \ sec^{-1})$
$0.1$	$0.1$	$5 \times 10^{-6}$
$0.2$	$0.1$	$10^{-5}$
$0.2$	$0.2$	$4 \times 10^{-5}$

Calculate the rate constant of the reaction (in $M^{1-n} \ sec^{-1}$),where $n$ is the order of the reaction.

$A$ study of chemical kinetics of the reaction $A + B \to$ Products,gave the following data at $25 \ ^oC$.

$Exp. \ No.$	$[A]$	$[B]$	$Rate$
$1.$	$1.0$	$0.15$	$4.2 \times 10^{-6}$
$2.$	$2.0$	$0.15$	$8.4 \times 10^{-6}$
$3.$	$1.0$	$0.20$	$5.6 \times 10^{-6}$

Find out the rate law.

For the gaseous reaction,$N_2O_5 \rightarrow 2NO_2 + \frac{1}{2}O_2$,the rate can be expressed as:
$-\frac{d[N_2O_5]}{dt} = K_1[N_2O_5]$
$+\frac{d[NO_2]}{dt} = K_2[N_2O_5]$
$+\frac{d[O_2]}{dt} = K_3[N_2O_5]$
The correct relation between $K_1, K_2$ and $K_3$ is:

The order of a reaction with rate equals $k[C_A]^{3/2} [C_B]^{-1/2}$ is

For the reaction $A + B \rightarrow$ products,it is observed that
$(i)$ on doubling the initial concentration of $A$ only,the rate of reaction is also doubled and
$(ii)$ on doubling the initial concentration of both $A$ and $B$,there is a change by a factor of $8$ in the rate of the reaction.
The rate of this reaction is given by