Answer:
246.67 min
Step-by-step explanation:
Half life is the time at which the concentration of the reactant reduced to half.
Half life expression for first order kinetic is: 
 
 
Where, k is rate constant 
So, 
Given that;- k = 
 (Values corrected from source)
 (Values corrected from source)
Thus, 
 
 

246.67 min is the half-life of the reaction.