For the elementary reaction M ⟶ N, the rate of disappearance of M increases by a factor of 8 upon doubling the concentration of M. The order of the reaction with respect to M is
(IIT-JEE-Advanced 2014)
r1=K[M]x
8r1=K[2M]x …(ii)
⇒18=(12)x⇒(12)3=(12)x⇒x=3.