Chapter 7 Practice Paper: Particulate Nature of Matter — mark scheme (print)

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QQ/S1SCI/CH7

Secondary 1 · Lower Secondary Science (G2 / G3)

Mark scheme

Particulate Nature of Matter

Chapter 7 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	ASolid particles are close together in a regular arrangement and vibrate about fixed positions.	1
2	CGas particles are far apart and move quickly and randomly.	1
3	BThe colour starts concentrated in the drop. More particles move out into the water than move back, so the colour spreads upwards.	1
4	DThe tin is sealed, so warming does not add or remove particles. The mass stays the same while the tin expands.	1
5	CMelting is a physical change of the same substance. Particles that were vibrating in fixed positions become free to slide past each other. No new substance forms, and the mass does not disappear.	1
6	BEvaporation at the surface can happen below the boiling point. The wind carries water particles away, so the kit dries without the water boiling.	1
7	DThe particles move faster and take up more space. The number of particles does not change.	1
8	BA liquid keeps its volume but its shape changes to fit the container.	1
9	AThe circles are a model that helps explain how the ice behaves. They are not a photograph of the particles.	1
10	CEvaporation can happen at the surface below the boiling point.	1

Section B: Structured questions[20 marks]

Question	Answer and marking points	Marks
1(a)	The particles stay close together, so the volume hardly changes. They can slide past each other, so the squash takes the shape of the glass. Particles stay close together, so the volume stays about the same [1] They can slide, so the liquid takes the shape of the glass [1]	2
1(b)	Some particles leave the surface and move quickly through the air, which has large gaps between its particles. Particles leave the squash and travel through the air [1] Air particles are far apart / the smell particles move quickly [1]	2
1(c)	No. The same particles move from where they are concentrated to where they are not. No new substance is needed [1]	1
	Total for Question 1	5
2(a)	Particles leave the crystal and move through the water, from where they are crowded to where there are fewer of them. Particles move through the water [1] From a higher concentration to a lower concentration [1]	2
2(b)	The colour would spread in less time. Warmer particles move faster, so they mix through the water sooner. It would spread faster / in less time [1] Particles move faster when warmer [1]	2
2(c)	No. The same particles have spread out. No new substance has formed. No new substance / the same particles have spread [1]	1
	Total for Question 2	5
3(a)	80 g [1]	1
3(b)	80 ÷ 100 = 0.80 g/cm³ 80 ÷ 100 [1] 0.80 g/cm³ [1]	2
3(c)	80 ÷ 125 = 0.64 g/cm³ 80 ÷ 125 [1] 0.64 g/cm³ [1]	2
3(d)	The particles are slightly further apart. Particles are further apart [1]	1
	Total for Question 3	6
4(a)	The particles should be close together, and they should be in a regular pattern rather than widely spaced. Close together, not widely spaced [1] Regular pattern / fixed positions [1]	2
4(b)	The particles in the solid were already vibrating. Warming does not remove particles, so the mass stays the same. Warming does not remove particles [1] The mass stays the same [1]	2
	Total for Question 4	4

— End of mark scheme —