Available practice: 71 of 75 marks. Parts 5(a)(ii), 5(b)(i), 11(a) await marking support. Scores cover available parts only. Theory Paper 2: Section A is compulsory and Section B offers a choice of two questions. Four published mark-scheme discrepancies across the two variants are held from automatic marking.
(a)A beaker is filled with water and placed on a hot-plate to boil, as shown in Fig. 4.1. The hot-plate is on top of a balance, which measures the mass of water in the beaker. The liquid boils for a long time. There are bubbles within the boiling water. State what is inside each bubble.
Answer guidance
State A short answer. No explanation is needed, and adding one cannot earn extra marks.
[1 mark]
(b)A beaker is filled with water and placed on a hot-plate to boil, as shown in Fig. 4.1. The hot-plate is on top of a balance, which measures the mass of water in the beaker. The liquid boils for a long time. There are bubbles within the boiling water. The mass of water is measured at two different times, while the water is boiling steadily. During this time • the mass of water in the beaker decreases by 20 g • the energy supplied to the hot-plate is 52 000 J • the energy lost from the hot-plate and beaker to the atmosphere is 6000 J Calculate the specific latent heat of vaporisation of water.
[3 marks]
(c)A beaker is filled with water and placed on a hot-plate to boil, as shown in Fig. 4.1. The hot-plate is on top of a balance, which measures the mass of water in the beaker. The liquid boils for a long time. There are bubbles within the boiling water. The beaker of water is taken off the hot-plate. The boiling stops but evaporation still continues and the water cools. Explain, using ideas about molecules, how evaporation causes cooling.
Answer guidance
Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.
[2 marks]
5054/22/M/J/16Cambridge O Level Physics 5054 · May/June 2016 · Paper 2 variant 2 · Question 4