please help with C i need it to be correct

The substitution of CO in Ni(CO)4 by another molecule L (where L is an electron-pair donor such as P(CH3)x ] was studied some years ago and led to an understanding of some of the general principles that govern the chemistry of compounds having metal-CO bonds, (See J. P. Day, F. 8asolo, and R. G. Pearson: Joumal of the American Chemical Society, Vol, 90,p,6927,1968.) A detalled study of the kinetics of the reaction led to the following mechanism: Slow Ni(CO)4Ni(CO)3+CO Fast Ni(CO)3+LNi(CO)3L a. What is the molecularity of each of the elementary reactions? Molecularity of the slow step = Molecularity of the fast step = b. Doubling the concentration of Ni(CO)4 increased the reaction rate by a factor of 2 . Doubling the concentration of I. had no effect an the reaction rate. Based on this information, write the rate equation for the reaction, (Use k for the rate constant.) Rate = c. The experimental rate constant for the reaction, when L=P(C4H5)s, is 9.3103s1 at 20C. If the initiol concentration ot Ni( COO) is 0.021.3, what is the concentration of the product after 6.0 minutes? Concentration =