MHT CET202618 April 2026Evening ShiftChemistryChemical KineticsActual
What is the time required for 75 % completion of a first order reaction if rate constant is 23.03 minute ⁻¹ ?
Options
- A12.00 s
- B3.6 s
- C36 s
- D6.0 s
Correct answer
B. 3.6 s
Step-by-step solution
For a first order reaction, the time required for a given completion is given by: t = 2.303 k ( a a-x ) Given k = 23.03 min ⁻¹ and for 75 % completion, x = 0.75a . t = 2.303 23.03 ( a a - 0.75a ) t = 0.1 ( 1 0.25 ) t = 0.1 4 t = 0.1 0.602 = 0.0602 min Converting the time into seconds: t = 0.0602 60 s = 3.612 s 3.6 s Answer: 3.6 s