Chemical Kinetics Part 1

For the first order reaction A→2B,1 mole of reactant A gives 0.2 moles of B after 100 minutes. The half life of the reaction is ...... min. (Round off to the nearest integer).
[Use : ln‌2=0.69,ln‌10=2.3
Properties of logarithms : ln‌xy=y‌ln‌x;
ln(

x

y

)=ln‌x−ln‌y]
(Round off to the nearest integer)