Which of the following statements is incorrect?

If the reaction between $A$ and $B$ to give $C$ shows first-order kinetics in $A$ and second-order in $B$,the rate equation can be written as:

The following are the rate constants of two different reactions. Determine the overall order of reaction for each case:
$(a)$ $6.66 \times 10^{-3} \, s^{-1}$
$(b)$ $4.5 \times 10^{-2} \, mol^{-1} \, L \, s^{-1}$

Which one of the following is wrongly matched?

The reaction of hydrogen and iodine monochloride is given as
$H_{2(g)} + 2ICl_{(g)} \to 2HCl_{(g)} + I_{2(g)}$
This reaction is of first order with respect to $H_{2(g)}$ and $ICl_{(g)}$. Which of the following mechanisms is consistent with the given information?
Mechanism $A$:
$H_{2(g)} + 2ICl_{(g)} \to 2HCl_{(g)} + I_{2(g)}$
Mechanism $B$:
$H_{2(g)} + ICl_{(g)} \to HCl_{(g)} + HI_{(g)}$ (Slow)
$HI_{(g)} + ICl_{(g)} \to HCl_{(g)} + I_{2(g)}$ (Fast)

For a chemical reaction $A \rightarrow B$,the rate of the reaction is $2 \times 10^{-3} \ mol \ dm^{-3} \ s^{-1}$,when the initial concentration is $0.05 \ mol \ dm^{-3}$. The rate of the same reaction is $1.6 \times 10^{-2} \ mol \ dm^{-3} \ s^{-1}$ when the initial concentration is $0.1 \ mol \ dm^{-3}$. The order of the reaction is