to completed 60% reaction
Ans. 112.7 min
Half -life of first order reaction can be given by
t1/2 =0.693/k
for first order reaction :
let a=100
x= 25 (given)
time =5min
applying in above equation, we get
thus for half life
t1/2 =0.693/0.05704
Ans. 12.14 min.
Since it is first order, thus