$A$ reaction involving different reactants can never be a/an......?

The rate of reaction,$A + B \rightarrow \text{product}$,is $7.2 \times 10^{-2} \ mol \ dm^{-3} \ s^{-1}$ at $[A] = 0.4 \ mol \ dm^{-3}$ and $[B] = 0.1 \ mol \ dm^{-3}$. The reaction is first order in $A$ and second order in $B$. Calculate the rate constant.

For the reaction between $A$ and $B$,the initial rate of reaction $(r_0)$ was measured for different initial concentrations of $A$ and $B$ as given below. Determine the order of the reaction with respect to $A$ and $B$ respectively.

$[A] / mol \ L^{-1}$	$0.2, 0.2, 0.4$
$[B] / mol \ L^{-1}$	$0.3, 0.1, 0.05$
$r_0 / mol \ L^{-1} s^{-1}$	$5.0 \times 10^{-5}, 5.0 \times 10^{-5}, 1.4 \times 10^{-4}$

For the reaction $A + B \rightarrow C$,select the appropriate rate law based on the following data:
$1$. $[A] = 0.012, [B] = 0.035 \rightarrow \text{Initial Rate} = 0.10$
$2$. $[A] = 0.024, [B] = 0.070 \rightarrow \text{Initial Rate} = 1.6$
$3$. $[A] = 0.024, [B] = 0.035 \rightarrow \text{Initial Rate} = 0.20$
$4$. $[A] = 0.012, [B] = 0.070 \rightarrow \text{Initial Rate} = 0.80$

If the half-life of a reaction is halved when the initial concentration of the reactant is doubled,what is the order of the reaction?

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