During a marathon, a runner's body is cooled by the evaporation of sweat from their skin.
Which molecules escape from the liquid sweat during evaporation, and what happens to the average kinetic energy of the remaining sweat molecules?
Escaping molecules: the ones with higher kinetic energy; Average kinetic energy of remaining molecules: decreases
Escaping molecules: the ones with higher kinetic energy; Average kinetic energy of remaining molecules: increases
Escaping molecules: the ones with lower kinetic energy; Average kinetic energy of remaining molecules: decreases
Escaping molecules: the ones with lower kinetic energy; Average kinetic energy of remaining 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.