For a first order reaction at $27^{\circ} C$,the ratio of time required for $75 \%$ completion to $25 \%$ completion of reaction is

For a first order reaction,the initial concentration of a reactant is $0.05 \ M$. After $45 \ minutes$,it is decreased by $0.015 \ M$. Calculate the half-life period $(t_{1/2})$ (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?

$A$ particular reaction has a rate constant $1.15 \times 10^{-3} \,s^{-1}$. How long does it take for $6 \,g$ of the reactant to reduce to $3 \,g$ (in $\,s$)? $(\log 2 = 0.301)$

In a first order reaction,the concentration of the reactant decreases from $20 \ mmol$ to $10 \ mmol$ in $1.151 \ min$. What is the rate constant (in $min^{-1}$)?

Time required for $90 \%$ completion of a first order reaction is '$x$' minute. Calculate the time required to complete $99.9 \%$ of the reaction at the same temperature.