The plot of $t_{1/2}$ versus $[R]_0$ for a reaction is a straight line parallel to the $x$-axis. The unit for the rate constant of this reaction is:

Which of the following is a correct statement for a first-order reaction?

The inactivation rate of a viral preparation is proportional to the amount of virus. In the first minute after preparation,$10 \%$ of the virus is inactivated. The rate constant for viral inactivation is $..... \times 10^{-3} \ min^{-1}$. (Nearest integer)
[Use : $\ln 10 = 2.303; \log_{10} 3 = 0.477; \text{property of logarithm} : \log x^y = y \log x$]

For a first order reaction,to obtain a positive slope,we need to plot $...$ where $[A]$ is the concentration of reactant $A$.

In the following first order reactions $A$ $\xrightarrow{K_1} B$ $\xrightarrow{K_2} \text{Product}$,find the ratio $K_1/K_2$ if $90\%$ of $A$ has been reacted in time $t$ while $99\%$ of $B$ has been reacted in time $2t$.

Half-life of a first order reaction is $20 \ s$ and initial concentration of reactant is $0.2 \ M$. The concentration of reactant left after $80 \ s$ is (in $M$)