A thermometer has no scale. Where must the bulb of this thermometer be placed to determine the upper fixed point of 100∘C100^\circ\text{C}100∘C on the Celsius scale?
in a mixture of ice and salt
in pure melting ice
in steam above pure boiling water at standard atmospheric pressure
in a refrigerator
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.