States of Matter

4 questions, 21 marks, every one with its mark scheme, 2 of them Higher Tier or Extended only.

Or open them one at a time, as you finish each question.

Question 1

11 marks

The table shows the melting points and boiling points of four substances.

Substance	Melting point / °C	Boiling point / °C
butane	−138	−1
gallium	30	2400
hexane	−95	69
naphthalene	80	218

1(a)[1 mark]

Give the name of the substance that is a gas at 20 °C.

Mark scheme

butane1

1(b)[2 marks]

Deduce the physical state of gallium at 50 °C. Explain your answer using the data in the table.

Mark scheme

liquid1
melting point is below 50 °C and boiling point is above 50 °C1

1(c)[4 marks]

Complete the table to describe the particles in solid naphthalene, liquid hexane and gaseous butane.

State	Separation of particles	Arrangement of particles	Motion of particles
solid	touching
liquid		random	random, moving past each other
gas	far apart		random, moving quickly in all directions

Mark scheme

regular1
vibrate about fixed positions1
touching1
random1

1(d)[2 marks]

Gaseous naphthalene at 250 °C is cooled to 20 °C.

Name the two changes of state that take place, in the order in which they happen.

Mark scheme

condensation1
freezing1

1(e)[2 marks]

A thin layer of hexane is left in an open dish at 20 °C. The hexane slowly disappears by evaporation.

Give two differences between evaporation and boiling.

Mark scheme

boiling happens at a specific temperature, evaporation happens over a range of temperatures1
boiling happens throughout the liquid, evaporation is a surface process1

Question 2

3 marks

A gas cylinder in a closed storeroom develops a small leak. There is no movement of air in the storeroom. After some time the gas is detected in every part of the storeroom.

2(a)[1 mark]

Name the process by which the gas spreads through the storeroom.

Mark scheme

diffusion1

2(b)[2 marks]

Describe this process in terms of particles.

Mark scheme

particles move randomly1
particles move from an area of high to low concentration1

Question 3

Extended4 marks

A storeroom contains cylinders of four different gases. A gas detector is fixed to a wall at the same distance from each cylinder.

Gas	Formula
chlorine	Cl₂
hydrogen sulfide	H₂S
methane	CH₄
sulfur dioxide	SO₂

3(a)[1 mark]

All four cylinders leak at the same time. Which gas reaches the detector first?

Tick (✓) one box.

chlorine
hydrogen sulfide
methane
sulfur dioxide

Mark scheme

methane1

3(b)[1 mark]

Explain your answer to 03.1.

Mark scheme

methane has the lowest relative molecular mass1

3(c)[2 marks]

A cylinder of ammonia, NH₃, is added to the storeroom.

Deduce whether ammonia diffuses faster or slower than hydrogen sulfide. Give a reason for your answer.

Mark scheme

faster1
ammonia has a lower relative molecular mass (17) than hydrogen sulfide (34)1

Question 4

Extended3 marks

A student heats a sample of a solid until it is completely molten. The student then lets the liquid cool and records its temperature every minute.

Time / min	0	1	2	3	4	5	6	7	8	9
Temperature / °C	92	84	77	71	69	69	69	69	63	56

4(a)[1 mark]

Use the data to deduce the melting point of the substance.

Mark scheme

69 °C1

4(b)[1 mark]

From 4 minutes to 7 minutes the temperature stays the same. Name the change of state happening during this time.

Mark scheme

freezing1

4(c)[1 mark]

The student plots a cooling curve of temperature against time.

Describe the shape of the curve between 4 minutes and 7 minutes.

Mark scheme

horizontal line1

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