The thermal decomposition of phosphine (PH3) into phosphorus and molecular hydrogen is a f...

The thermal decomposition of phosphine (PH3) into phosphorus and molecular hydrogen is a first-order reaction:

The half-life of the reaction is 35.0 s at 680°C. Calculate (a) the first-order rate constant for the reaction and (b) the time required for 95 percent of the phosphine to decompose.