177Doc Scientia - Textbook and Workbook - Natural Sciences - Grade 8

Unit 2: Particle model of matter

Multiple-choice questions

Four possible answers are given for the following questions. Each question has only ONE correctanswer. Choose the correct answer and mark the applicable LETTER with a cross (X).

1. Which graph best represents the relative distance between the particles of most substances in their solid, liquid, and gas states?

KEY:

A. B.

C. D.s ℓ g

closetogether

farapart

solid (s) liquid (ℓ) gas (g)

s ℓ g

s ℓ g

closetogether

farapart

s ℓ g

exam questions: particle model of matter

2. During which state change is heat energy absorbed by a substance? A. liquid to gas B. gas to solid C. liquid to solid D. gas to liquid

3. The diagram below shows a tall beaker with four different liquids and their densities. If a ball that has a density of 1,73 g.cm-3 is placed in the beaker, where will the ball come to rest? A. on top of liquid A B. between liquids B and C C. between liquids C and D D. at the bottom of the beaker

A. 0,89 g.cm-3

B. 1,00 g.cm-3

C. 1,21 g.cm-3

D. 2,34 g.cm-3

closetogether

farapart

closetogether

farapart

Unit 2

178 Doc Scientia - Textbook and Workbook - Natural Sciences - Grade 8

Matter and materials

4. The diagram alongside shows a model of a sample of gas particles at room temperature. Which diagram best shows the results of removing heat from this sample until it freezes?

A. B. C. D.

5. The diagram below shows a rock suspended above an overflow container filled with water up to the overflow spout. A graduated cylinder is positioned next to the container to collect water that comes out of the overflow spout. Which property of the rock can be directly determined when the rock is placed in the overflow container? A. mass B. density C. volume D. hardness

One word items

Give one word/term for each of the following descriptions.1. The process in which particles in liquids and gases move from a high concentrated area to an area with a lower concentration of the particles.2. The force created by gas particles hitting the walls of their container.3. Amount of mass in a given volume of matter.

Contextual questions

1. Draw a square and use circles to indicate the particles of each substance in the specific state.

2 Consider the following models, which show the particles within a substance, during different states.2.1 Name each of the changes (A–F).2.2 Name a known substance that sublimes.

overflow spout

graduatedcylinder

rock

overflowcontainer

solid liquid gas

A B

D C

E

F

179Doc Scientia - Textbook and Workbook - Natural Sciences - Grade 8

Unit 2: Particle model of matter

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180 Doc Scientia - Textbook and Workbook - Natural Sciences - Grade 8

Matter and materials

3 Say whether energy is ADDED or REMOVED to bring about the phase change in each situation. 3.1 3.2

3.3 Explain how EVAPORATION differ from BOILING.3.4 Explain why the word BOIL does not necessarily mean that a substance is hot.3.5 Explain why the word FREEZE does not necessarily mean that a substance is cold.3.6 The particle model of matter is a theory of how the particles of all matter behave. List the six important statements of this model.

4 Consider the different states of water.

Write down only the letter (A, B or C) of the state:4.1 where the kinetic energy is greatest;4.2 where particles only vibrate in a fixed position;4.3 which can be easily compressed;4.4 where the forces between the particles are the strongest;4.5 in which diffusion will occur the fastest.

5 The graph of temperature versus time for a substance which is heated and cooled is shown.

5.1 Name the vertical and horizontal axes respectively.

A. B. C.

D

A

C

B