Which equation represents the $1/4^{th}$ life for a first-order reaction?

$A$ flask is filled with equal moles of $A$ and $B$. The half-lives of $A$ and $B$ are $100 \, s$ and $50 \, s$ respectively and are independent of the initial concentration. The time required for the concentration of $A$ to be four times that of $B$ is $.... \, s.$
(Given : $\ln 2 = 0.693$ )

In a first order reaction,the concentration of the reactant is reduced from $0.6 \ mol \ L^{-1}$ to $0.2 \ mol \ L^{-1}$ in $5 \ min$. What is the rate constant of the reaction (in $min^{-1}$)? $(\log 3 = 0.4771)$

If the rate constant for a first order reaction is $k$,then find the time required for completion of $80 \%$ of the reaction.

If the rate constant for a first order reaction is $k$,the time $(t)$ required for the completion of $99 \%$ of the reaction is given by

For a first order reaction $(A) \rightarrow$ products,the concentration of $A$ changes from $0.1 \ M$ to $0.025 \ M$ in $40 \ min$.
The rate of reaction when the concentration of $A$ is $0.01 \ M$ is ............$ \times 10^{-4} \ M/min$.