Answer: Δn for the reaction is zero.
- A Δn for the reaction is zero
- B Δn is positive
- C Δn is negative
- D For all gaseous reactions
Correct answer: A. Δn for the reaction is zero
Explanation: Units of Kc depend on (concentration)Δn; when Δn = 0 the units cancel and Kc is dimensionless.
As the reaction proceeds, reactant concentration falls and product concentration rises until both level off at equilibrium.
Concept context
When forward and reverse reaction rates are equal, equilibrium is reached. Learn about Kc, Kp, Le Chatelier's principle, and acid-base equilibria, including pH, buffer solutions, and solubility product.