The rate of the first-order reaction `X rarr` products is `7.5 xx 10^(-4) mol L^(-1) "min"^(-1)`. What will be value of rate constant when the concentration of `X` is `0.5 mol L^(-1)` ?

Options

A. `3.75 xx 10^(-4)s^(-1)`
B. `2.5 xx 10^(-5) s^(-1)`
C. `1.5 xx 10^(-3) s^(-1)`
D. `8.0 xx 10^(-4) s^(-1)`

Answer

B

Explanation

Rate of reaction `= 7.5 xx 10^(-4) "mol L"^(-1) "min"^(-1)`
`= (7.5 xx 10^(-4))/(60) "mol L"^(-1) s^(-1)`
`= 1.25 xx 10^(-5) "mol L"^(-1) sec^(-1)`
Rate of reaction `= k["concentration of react ant X"]`
Or `k = (1.25 xx 10^(-5))/(0.5) = 2.5 xx 10^(-5) s^(-1)`