The reaction A `to`B follows first order reaction. The time taken for 0.8 mole of A to produce 0.6 mole of B is 1 hour. What is the time taken for conversion of 0.9 mole of A to produce 0.675 moles of B?

Options

A. 2 hours
B. 1 hour
C. 0.5 hour
D. 0.25 hour

Answer

B

Explanation

`A to B` For a first order reaction Given a=0.8 mol, (a - x)=0.8 - 0.6 = 0.2
`k=(2.303)/(1)log (0.8)/(0.2)` or `k=2.303 log 4`
again a = 0.9, a - x=0.9 - 0.675 = 0.225
`k=(2.303)/(t)log (0.9)/(0.225)`
`2.303 log 4=(2.303)/(t) log 4`
Hence t = 1 hour