For the reaction $A \to \text{Products}$,the rate of reaction becomes one-fourth when the concentration of $A$ is halved. What is the order of the reaction?

Reaction : $2Br^{-} + H_2O_2 + 2H^{+} \to Br_2 + 2H_2O$
takes place in two steps :
$(a)$ $Br^{-} + H^{+} + H_2O_2 \xrightarrow{slow} HOBr + H_2O$
$(b)$ $HOBr + Br^{-} + H^{+} \xrightarrow{fast} H_2O + Br_2$
The order of the reaction is

For a gaseous reaction between $X$ and $Y$,$X + 3Y \rightarrow XY_3$,the initial rate data is given below:
$[X] = 0.1 \ M, [Y] = 0.1 \ M, \text{Rate} = 0.002 \ Ms^{-1}$
$[X] = 0.2 \ M, [Y] = 0.1 \ M, \text{Rate} = 0.002 \ Ms^{-1}$
$[X] = 0.3 \ M, [Y] = 0.2 \ M, \text{Rate} = 0.008 \ Ms^{-1}$
$[X] = 0.4 \ M, [Y] = 0.3 \ M, \text{Rate} = 0.018 \ Ms^{-1}$
What is the rate law?

Velocity constant $K$ of a reaction is affected by

At a certain temperature,the half-life periods for the catalytic decomposition of $NH_3$ were found to be as follows:

Pressure $(mm \ Hg)$	$50, 100, 200$
Half-life period $(hrs)$	$3.52, 1.76, 0.88$

What will be the pressure when the half-life period is $2.5 \ hrs$?

Rate of the reaction $A + B \rightarrow \text{product}$ is $3.6 \times 10^{-2} \ mol \ dm^{-3} \ s^{-1}$ and rate law is $r = k[A][B]^2$. What is the rate constant of the reaction if $[A] = 0.2 \ M$ and $[B] = 0.1 \ M$?