Which of the following statements is true about the voltaic cell?

Identify the function of salt bridge.

A first order reaction complete $60$% in $20$ minutes. How long will the reaction take to complete $84$%?

The rate constant for a first order reaction is $60 \text{ s}^{-1}$. How much time will it take to reduce the concentration of the reactant to $1/20^{\text{th}}$ of its initial value?