For any chemical reaction,what factors do chemists aim to determine?

Which of the following statements is correct?

Under identical reaction conditions,for a reactant with an initial concentration of $1.386 \, M$,the time taken for the concentration to become half is $40 \, s$ for a first-order reaction and $20 \, s$ for a zero-order reaction. The ratio of the rate constant of the first-order reaction $(K_1)$ to the rate constant of the zero-order reaction $(K_0)$ is ......... $mol \, L^{-1}$.

Half-lives of a first order and a zero order reaction are same. Then the ratio of the initial rates of first order reaction to that of the zero order reaction is

The effect of $pH$ on the rate constant for the hydrolysis of an ester is given by:

$t_{100\%}$ is the time required for the $100\%$ completion of the reaction, while $t_{1/2}$ is the time required for $50\%$ of the reaction to be completed. Which of the following options correctly represents the relation between $t_{100\%}$ and $t_{1/2}$ for zero and first-order reactions, respectively?