Answer:
The correct answer is 0.12.
Explanation:
 According the reaction kinetics we all know that
  Rate=k[A][B]
K= rate constant
[A] = Concentration of A
[B] =Concentration of B
   R=0.36mol/litre/sec
  K=?
K= rate÷[A][B]
  = 0.36÷3
  =0.12