The reaction 2N₂O₅ \(\rightleftharpoons\) 2N₂O₄ + O₂ is 

CONCEPT:

Order and Molecularity of Chemical Reactions

• Molecularity refers to the number of reactant molecules involved in an elementary step of the reaction.
• Order of reaction is the sum of the powers of the concentration terms in the rate equation.
• A reaction can be unimolecular, bimolecular, or trimolecular based on the number of molecules involved.
• The order of reaction can be zero, first, second, etc., based on how the rate depends on the concentration of reactants.

EXPLANATION:

• Consider the given reaction:

  2N₂O₅ ⇌ 2N₂O₄ + O₂

• For the reaction:
  • The reaction involves two molecules of N₂O₅ as reactants, making it bimolecular.
  • The given reaction is described as first order, indicating that the rate of reaction depends linearly on the concentration of N₂O₅.
• Therefore, the correct classification for the reaction is bimolecular and first order.

Therefore, the correct answer is option 3.