Answer:
e. 22s
Explanation:
Initial Concentration = 100
Final concentration = 15 ( Since the reaction is 85% complete)
Time = 12 minutes = 720 seconds
The integrated rate law for second order reactions is given as;
1 / [A] = (1 / [A]o) + kt
Making k subject of interest, we have;
kt = (1 / [A] ) - (1 / [A]o )
k = (1 / [A] ) - (1 / [A]o ) / t
k = [(1/ 15) - (1 / 100) ] / 720
k = (0.0667 - 0.01 ) / 720
k = 0.0567 / 720
k = 7.875e^-5
How long would it take for the reaction to be 15% complete?
Final concentration = 85 (Since the reaction would be 15% complete)
The integrated rate law for second order reactions is given as;
1 / [A] = (1 / [A]o) + kt
Making t subject of interest, we have;
kt = (1 / [A] ) - (1 / [A]o )
t = (1 / [A] ) - (1 / [A]o ) / k
t = [(1 / 85 ) - (1 / 100) ] / 7.875e^-5
t = (0.0117 - 0.01 ) / 7.875e^-5
t = 0.001765 / 7.875e^-5
t = 22.41 seconds
Corect option = E.
is 
, hence one 
is 
, thus 
is 