(a) Where do these water droplets come from? (b) What happens to the ice cubes after they are left in the glass for some time? (c) If we heat water, what will happen to it?
The water droplets come from the water vapour in the air. When the cold glass cools the surrounding air, the water vapour condenses into liquid water droplets on the glass surface.
The ice cubes melt and change from solid form into liquid water.
When water is heated, it boils and changes into water vapour (steam), which is the gaseous form of water.
Explanation
(a) The chapter explains through Activity 2 that water vapour in the air condenses on cold surfaces. (b) The chapter demonstrates that ice (solid) changes to water (liquid) when it melts. (c) The chapter shows that heating water causes it to change into vapour form.