A first order reaction takes 40 min for 30% completion. Calculate `t_(1/2)`.

A first order reaction takes 40 minutes for 20% completion. Calculate its half life period.

A first order reaction takes 30 minutes for 50 % completion. Calculate the time required for 90 % completion of the reaction.

A first order reaction takes 69.3 minutes for 50% completion. Calculate time required for 80% completion of the reaction.

A first order reaction takes 69.3 minutes for 50% completion. Calculate the time required for 80% completion of the reaction.

A first order reaction takes 69.3 minutes for 50 % completion. Calculate time required for half change of reaction.

A first order reaction takes 23.1 minutes for 50% conmpletion. Calculate the time required for 75% completion of this reaction (log 2 = 0. 301) , ( log 3 = 0. 4771) ( log 4 = 0.6021)