MHT CET202618 April 2026Evening ShiftChemistryChemical KineticsActual
Which of the following is an example of fractional order reaction ?
Options
- A2 H ₂ O ₂ (g) 2 H ₂ O (l) + O ₂ (g)
- BH ₂ (g) + I ₂ (g) 2 HI (g)
- CCH ₃ CHO (g) CH ₄ (g) + CO (g)
- D2 NO (g) + 2 H ₂ (g) N ₂ (g) + 2 H ₂ O (l)
Correct answer
C. CH ₃ CHO (g) CH ₄ (g) + CO (g)
Step-by-step solution
The decomposition of acetaldehyde ( CH ₃ CHO ) is a well-known example of a fractional order reaction. The experimentally determined rate law for this reaction is given by: Rate = k[ CH ₃ CHO ]^ 1.5 Thus, the overall order of the reaction is 1.5 , which is a fractional value. For the other given reactions: Decomposition of H ₂ O ₂ is a first-order reaction. Formation of HI from H ₂ and I ₂ is a second-order reaction. Reaction between NO and H ₂ is a third-order reaction. Answer: CH ₃ CHO (g) CH ₄ (g) + CO (g)