the rate laws were determined for the following reactions: Reaction 1: rate= k[A] ^2
reaction 2 rate = k [A] [B] ^1/2
reaction 3 rate = k [A]^2 [b]^2
reaction 4 rate k= [A] [B] ^2
reaction 5 rate= K= [A] ^2 [B]^-1
give the number of reactions that can be elementary reactions?? which ones are the right ones and why?