MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The order of a reaction is determined experimentally by its rate law. For the decomposition of hydrogen peroxide, the rate law is Rate = k[ H _2 O _2]. It is a first-order reaction. For the thermal decomposition of acetaldehyde, the rate law is Rate = k[ CH _3 CHO ]^ 1.5 . It is a fractional-order (1.5) reaction. For the reaction between NO _2 and F _2, the mechanism involves a slow rate-determining step: NO _2 + F _2 NO _2 F + F . The rate law is Rate = k[ NO _2][ F _2]. The overall order is 1 + 1 = 2, making it a second-order reaction. For the reaction between NO and H _2, the rate law is Rate = k[ NO ]^2[ H _2]. The overall order is 2 + 1 = 3, making it a third-order reaction. Thus, 2\, NO _ 2(g) + F _ 2(g) 2 NO _2 F _ (g) is the correct example of a second-order reaction. Answer: 2\, NO _ 2(g) + F _ 2(g) 2 NO _2 F _ (g)