For a first-order reaction,it takes $40 \ min$ for $90\%$ completion. The half-life of the reaction is ..... (in $min$)

The thermal decomposition of a molecule follows a first-order reaction. The molecule decomposes $50\%$ in $120 \text{ minutes}$. How many minutes will it take for $90\%$ decomposition?

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 the reaction $2A + B \to \text{product}$,the rate law is given by $\frac{-d[A]}{dt} = k[A]$. At a time $t = \frac{t_{1/2}}{\ln 2}$,what is the concentration of the reactant $A$?

$A$ first order reaction is $75 \%$ completed in $60 \ min$. The time required for its $50 \%$ completion is: (in $min$)

In a first order reaction,the concentration of the reactant is reduced to $12.5 \%$ in one hour. When was it half completed?