Which observation gives the strongest evidence that a change is physical rather than chemical?
The change gives out energy to the surroundings
The substance changes colour during the change
Bubbles of gas are seen during the change
The original substance can easily be recovered
84 exam-style questions on Edexcel GCSE Chemistry 3.1 States of matter, covering 3.1.1 The three states of matter and changes of state. Each one has a worked solution and a mark scheme showing where the marks go.