For a first order reaction at `27^@`C, the ratio of time required for 75% completion to 25% completion of reaction is

Options

A. 3
B. 2.303
C. 4.8
D. 0.477

Answer

C

Explanation

For a first order reaction,
`t= 2.303/lambda "log" a/(a-x)`
Let, a = 100,
` therefore t_(1)/t_(2) = (2.303/lambda xx "log" 100/(100-75))/ (2.303/lambda xx "log" 100/(100-25))`
`implies "log"4/"log"(4/3)= "log"4/("log"4-"log"3)`
`therefore t_(1)/t_(2)=4.81`