Chapter 2 Practice Paper: Heat Transfer — mark scheme (print)

QuizQuipPractice Series

QQ/S2SCI/CH2

Secondary 2 · Lower Secondary Science (G2 / G3)

Mark scheme

Heat Transfer

Chapter 2 Practice Paper · Maximum mark: 30

Notes for markers

Award one mark for each point marked [1], up to the marks shown for the part.
Accept answers worded differently that show the same understanding.
Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

Question	Answer
1	AThe kelvin is the SI unit of temperature. School thermometers are usually marked in degrees Celsius.	1
2	CThe solid metal passes energy from particle to particle along the handle. That is conduction.	1
3	BThe rising air is a gas, and the same kind of flow can happen in a liquid. A vacuum and a solid block cannot flow.	1
4	DRadiation does not need particles, so sunlight can cross the empty space around the satellite.	1
5	ADull, dark surfaces emit and absorb radiation better than shiny, light surfaces.	1
6	CThe warmer water expands, becomes less dense, and rises. Cooler water sinks.	1
7	DThe metal gate gets longer when it is hot. The gap gives it room so the latch still closes.	1
8	BAir trapped in the foam conducts poorly, so heat from the room reaches the ice slowly.	1
9	AConduction and convection need particles. A vacuum has almost none. Shiny walls reduce radiation.	1
10	CThe shiny foil reflects infrared radiation, so less heat leaves the box that way.	1

Section B: Structured questions[20 marks]

Question	Answer and marking points	Marks
1(a)	Convection [1]	1
1(b)	The warmer water expands and becomes less dense than the cooler water, so it rises. It expands / becomes less dense [1] The less dense water rises [1]	2
1(c)	The particles in a solid cannot flow past each other. Heat travels through the solid by conduction. Solid particles cannot flow [1] Heat transfer in the solid is by conduction [1]	2
	Total for Question 1	5
2(a)	Can P, the dull black can. Dull black can / can P [1]	1
2(b)	A dull black surface emits radiation faster than a shiny silver surface, so heat leaves can P faster. Dull black emits radiation better [1] Heat leaves faster [1]	2
2(c)	The energy travels by radiation. Radiation does not need particles, so it can cross the empty gap. Radiation [1] Radiation does not need particles / can cross a vacuum [1]	2
	Total for Question 2	5
3(a)	30 g [1]	1
3(b)	30 ÷ 4.0 = 7.5 g/cm³ 30 ÷ 4.0 [1] 7.5 g/cm³ [1]	2
3(c)	30 ÷ 5.0 = 6.0 g/cm³. The density has fallen. 6.0 g/cm³ [1] The density has fallen [1]	2
	Total for Question 3	5
4(a)	Conduction and convection. Conduction [1] Convection [1]	2
4(b)	They reflect radiation. Shiny surfaces are poor emitters and poor absorbers. They reflect radiation / are poor emitters [1] Less heat is transferred by radiation [1]	2
4(c)	Air is a poor conductor, so heat from the room reaches the drink slowly. [1]	1
	Total for Question 4	5

— End of mark scheme —