1) A reaction: A2+B → products, involves the following mechanism $A_{2}\rightleftharpoons 2A$ (fast) (a being the intermediate) A+B $\overrightarrow{k_{2}}$ Products (slow) The rate law consistent to this mechanism is A) $rate =k[A_{2}][B]$ B) $rate =k[A_{2}]^{2}[B]$ C) $rate =k[A_{2}]^{1/2}[B]$ D) $rate =k[A_{2}][B]^{2}$ Answer: Option CExplanation: from slow step : rate = k2 [A][B] .............(i) From fast step : $K_{e}=\frac{[A]^{2}}{[A_{2}]} or [A] = K^{1/2}_{e}[A]^{1/2}$ ...........(ii) From (i) and (ii) rate = $k_{2}k_{e}^{1/2}[A_{2}]^{1/2}[B]=k[A_{2}]^{1/2}[B]$
