Answers to Q37 & Q38 & Important Water Cycle concepts

P5 SA2 Practice Paper Set 1 
Answers to Q37 & 38 
37a) He is incorrect. The mass of the water remains unchanged. (1m) However, the warmer water vapour from the surrounding loses heat as it touches the cooler surface of the beaker and condenses into water droplets, which increases the mass.

37b) The water vapour inside the car is warmer than the outside. (1m) So, the warmer water vapour touches the cooler surface of the windscreen, loses heat and condenses into water droplets l. (1m)

38a) Set-up A. (1m) The towel in A was not folded so its exposed surface area was the greatest. (1m)

38b) The greater the exposed surface area of the towel, the faster the rate of evaporation of water. (1m)

Important Water Cycle Concepts

1. Water gain heat and evaporates into water vapour. (Hot water vapour is used only when explaining boiling. For non-boiling situations, use warmer water vapour)
2. Water vapour loses heat and condenses into tiny water droplets. (Water vapour cannot condenses into clouds. Clouds are formed when more water droplets gathered together.)
3. Surrounding air is cooler  => There is a temperature difference => The greater the temperature difference, the faster the rate of condensation. Condensation can only take place when there is a temperature difference.
4. Evaporation takes place when there is a higher temperature in the surrounding or is windy.
5. Uses of water in plants, animals and humans.
6. Importance of reusing, reducing and recycling water.