Chemistry · May / June 2025 · Paper 12 · Question 17

Aqueous sodium thiosulfate reacts with hydrochloric acid. The rate of the reaction increases if the concentration of both reactants is increased. Nitrogen gas reacts with hydrogen gas. The rate of the reaction increases if the pressure in the reaction vessel is increased. Which row correctly explains why the given change increases the rate of the reaction?

1. Ahigher frequency of collisions between particles | higher frequency of collisions between particles
2. Bhigher frequency of collisions between particles | the activation energy is decreased
3. Cthe activation energy is decreased | higher frequency of collisions between particles
4. Dthe activation energy is decreased | the activation energy is decreased

As printed in the paper