A substance `''A''` decomposes in solution following the first order kinetics. Flask `I` contains `1L` of `1 M` solution of `A` and falsk `II` contains `100 mL` of `0.6 M` solution. After `8 hr`, the concentration, of `A` in flask `I` becomes `0.25 M`. What will be the time for concentration of `A` in flask `II` to become `0.3 M` ?

Options

A. 0.4 hr
B. 2.4 hrs
C. 4.0 hrs
D. unpredictable as rate constant is not given

Explanation

From date of flask I, `[A]_0= 1M_1[A]_t= 0.25M`
`k = 2.303/8 log. (1)/0.25`
`=2.303/8 log4 = 2.303/4 log2`
From date of flask II, `[A]_0= 0.6 M, [A]_t= 0.3 M`
`t = 2.303/k log. (0.6)/0.3= 2.303/k log 2 = (2.303 xx log2)/(2.303 xx log2)`.
= 4 hrs.