40% of a first order reaction is completed in 50 minutes. How much time will it take for the completion of 80% of this reaction?

Explanation

`k=(2.303)/(i)"log"_(10)(a)/(a-x)`
`=(2.303)/(50)"log"(100)/(60)`
`k=(2.303)/(50)xx0.2218`
`k=0.102 min^(-1)`
`t=(2.303)/(k)"log"(100)/(20)`
`t=(2.303)/(0.0102)xx0.6989`
`t=187.8`min