Marble chips react with dilute hydrochloric acid. A student measures the volume of gas every 30 seconds.

1. aWrite a word equation for the reaction. [1]
2. bDescribe how the rate changes as the reaction goes on, and explain why. [2]
3. cExplain, using particle theory, why powdered marble reacts faster. [2]

You'll mark your own answer against the marking guide when you hand it in.