Question

The graph below shows a curve obtained when water at 20℃ was heated for 15 mins.
         

1. What happens to the water molecules between points W and X 
2. In which part of the curve does a change of state occur?
3. Explain why the temperature does not rise between points X and Y 

Answer 1

1. Water molecules gain energy and move faster
2. XY
3. Supplied energy is used to break bonds between water molecules in liquid state and become free molecules in gaseous state