Order of a reaction is decided by

In a reaction,$A + B \rightarrow$ product,the rate is doubled when the concentration of $B$ is doubled,and the rate increases by a factor of $8$ when the concentrations of both the reactants $(A$ and $B)$ are doubled. The rate law for the reaction can be written as:

$A$ substance undergoes first-order decomposition. The decomposition follows two parallel first-order reactions as:
$A \xrightarrow{k_1} B$ $k_1 = 1.26 \times 10^{-4} \ s^{-1}$
$A \xrightarrow{k_2} C$ $k_2 = 3.8 \times 10^{-5} \ s^{-1}$
The percentage distribution of $B$ and $C$ are:

Which of the following rate laws has an overall order of $0.5$ for a reaction involving substances $x$,$y$,and $z$?

The reaction $2 A + B + C \longrightarrow D + E$ is found to be first order in $A$,second order in $B$,and zero order in $C$. What is the effect of increasing the concentration of all reactants twice?

The half-lives of two samples are $0.1 \ s$ and $0.4 \ s$. Their respective concentrations are $200$ and $50$. What is the order of the reaction?