Half life `.^87Ga` is 78 h.How long will it take to decay 21% of sample of Ga?

The half life a first order reaction is1.7hr.How long will it take for 20% of the reactant to react?

A radioactive isotope has a half life of T years : How long will it take the activity to reduce to 3.125%

A radioactive isotope has a half life of T years : How long will it take the activity to reduce to 1%of its original value?

The gaseous reaction A_2 rarr 2A is first order in A_2 . After 12.3 minutes 65% of A_2 remains undecomposed. How long will it take to decompose 90% of A_2 ? What is the half life of the reaction?

The rate constant of a first order reaction is 6.8xx10^(-4)s^(-1) . If the initial concentration of the reactant is 0.04 M, what is its molarity after 20 minutes? How long will it take for 25% of the reactant to react?

Mary cycles at the speed of 6 km/h. How long will she take to reach her aunt's house which is 12 km away? How long will she take, if she cycles at the speed of 4km/h?