Which of the following statements is $NOT$ correct regarding the order of 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?

For the reaction $2A + 2B \rightarrow 2C + D$,the rate law is expressed as $\text{rate} = k[A]^2[B]$. Calculate the rate constant if the rate of reaction is $0.24 \ mol \ dm^{-3} \ s^{-1}$ where $[A] = 0.5 \ M$ and $[B] = 0.2 \ M$.

In a reaction involving hydrolysis of an organic chloride in the presence of a large excess of water,$RCl + H_2O \to ROH + HCl$.

The unit of rate constant for a second-order reaction is usually expressed as: