A first order reaction with respect to reactant A has a rate constant 6.5 `min^(-1)`. If we start with 2.0 mol `L^(-1)` of A when would A reach the value 0.5 mol `L^(-1)`

Explanation

For first order reaction `k=(2.303)/(t) log ([A]_(0))/[A]` or `t=(2.303)/(k) log ([A]_(0))/[A]`
`t=(2.303)/(6.5 min^(-1)) log (2.0 mol L^(-1))/(0.5 mol L^(-1))=(2.303)/(6.5 min^(-1))log 4`
`=(2.303)/(6.5)xx0.6020 =0.213` min