A hiker keeps their drink cool by wrapping the flask in a wet cloth. Water evaporates from the wet cloth, which cools the flask. Which molecules escape from the water during evaporation and what happens to the average speed of the water molecules that remain in the cloth?
Escaping molecules: the more energetic ones; average speed of the remaining water molecules: decreases
Escaping molecules: the more energetic ones; average speed of the remaining water molecules: increases
Escaping molecules: the less energetic ones; average speed of the remaining water molecules: decreases
Escaping molecules: the less energetic ones; average speed of the remaining water molecules: increases
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.