Advanced Science Primary 4 Matter

Ravi placed two identical glasses of water, A and B, in a room. Glass A was covered with a lid while Glass B was left open. After two days, Glass B had less water than Glass A. Why?

A Evaporation cannot occur in a covered glass.
B The water in Glass B evaporated faster due to more surface area.
C The water in Glass A condensed and fell back into the glass.
D The water in Glass B gained more heat from the room.
Show Worked Solution

Worked Solution

Step 1: Evaporation occurs in both glasses. In Glass B, the water vapour escapes into the air. Step [2-9]: In Glass A, the water vapour hits the lid, loses heat, and condenses back into liquid droplets. Step [2-9]: These droplets fall back into the glass, so the water level remains almost the same in A.

Correct answer: The water in Glass A condensed and fell back into the glass.

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