During a marathon, a runner's skin is cooled as sweat evaporates from it.
Which molecules escape from the sweat during evaporation, and what happens to the average kinetic energy of the water molecules that remain on the runner's skin?
Escaping molecules: the less energetic ones; average kinetic energy of remaining molecules: increases
Escaping molecules: the less energetic ones; average kinetic energy of remaining molecules: decreases
Escaping molecules: the more energetic ones; average kinetic energy of remaining molecules: increases
Escaping molecules: the more energetic ones; average kinetic energy of remaining molecules: decreases
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.