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MHT CET202519 Apr 2025Evening ShiftChemistryChemical KineticsActual

Rate law for the reaction, C ₂ H ₅ I _ ( g ) C ₂ H _ 4( ~g ) + HI _ ( g ) is r = k [ C ₂ H ₅ ] What is the order and molecularity of this reaction?

Options

  1. Aorder and molecularity both are 1
  2. Border is 1 and molecularity is 2
  3. Corder and molecularity both are 2
  4. Dorder is 2 and molecularity is 1

Correct answer

A. order and molecularity both are 1

Step-by-step solution

Order of Reaction The rate law r = k[ C ₂ H ₅ I ] indicates first-order dependence on ethyl iodide concentration. The overall order is therefore 1. Molecularity The decomposition C ₂ H ₅ I _ (g) C ₂ H _ 4(g) + HI _ (g) involves a single reactant molecule, indicating unimolecular elementary step with molecularity 1. The reaction exhibits both first-order kinetics and unimolecular molecularity, corresponding to option A.

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