For which order reaction a straight line is obtained along with $x\,-$ axis by plotting a graph between half life $({t_{1/2}})$ and initial concentration $ 'a'$

In a reaction, the concentration of reactant is increased two times and three times then the increases in rate of reaction were four times and nine times respectively, order of reaction is

 $A + B \to $ products, it is found that the rate of the reaction is proportional to the concentration of $A,$  but it is independent of the concentration of $B$, then

The hydrolysis of ethyl acetate is a reaction of ......... order

$C{{H}_{3}}COOEt+{{H}_{2}}O\xrightarrow{{{H}^{+}}}C{{H}_{3}}COOH+EtOH$

The rate constant of esterification $(k) = k'\, [H_2O]$ rate constant of esterification $2.0\times 10^{-3}\,min^{-1}$ calculate  $k'$.

Consider the reaction, $2A + B \rightarrow$ products. When concentration of $B$ alone was doubled, the half-life did not change. When the concentration of $A$ alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is