At `27^(@)`C temperature, time required for 75% completion of a first order reaction is 20 seconds. What will be its rate constant?

Options

A. `0.693 "sec"^(-1)"mole"^(-1)` lt
B. `0.0693 "sec"^(-1)`
C. `0.693 "sec"^(-1)`
D. `0.693 "sec"^(-1)"mole"^(-1)` lt

Answer

B

Explanation

For 1st order Reaction:
`K= (1)/(t) ln""(Co)/(Ct) ` at75% completion: Ct=25%
`K= (2.303)/(20) log""(100)/(25):k= 0.0697 "sec"^(-1)`