# Particle model of matter - Short answer questions

Some short answer questions will be multiple choice questions. These will appear in both exam papers, and at both tiers. Multiple choice questions are asked as questions, often starting with 'What is …' or 'Which of these …'.

You have four options to choose from in a multiple choice question. You must only choose one of these options, by writing your answer (A, B, C, or D) in a box.

It may help to reject any answers that you feel are obviously wrong so that you can focus on choosing the right answer.

Other short answer questions will start with command words such as 'Describe' or 'Explain'. Some command words are easy to understand such as:

• 'Calculate' or 'Determine' for maths questions
• 'Complete' to fill in a gap in a table or graph
• 'Define' to give the meaning of an important word
• 'Suggest' where you use your knowledge in an unfamiliar situation

The command words 'Describe' and 'Explain' can be confusing. If you are asked to describe a graph, you will be expected to write about its overall shape, whether it is linear or curved, the slope of gradients etc. If you are asked to explain why a pattern or trend is seen in a graph, you will be expected to use your science knowledge, not just say what you see (which is a description), eg 'The graph shows a steep linear increase for the first three hours because…'.

'Explain how' and 'Why' questions often have the word 'because' in their answer. 'Describe' questions don't.

The number of marks per question part is given in this form '[2 marks]'. It is essential that you give two different answers if a question is worth two marks. Sometimes you can gain a second mark by giving the units in a calculation or stating specific data points, eg the speed of the object decreased by 8 m/s.

These questions have been written by Bitesize consultants as suggestions to the types of questions that may appear in an exam paper.

## Sample question 1 - Foundation

Question

A pupil wrote some notes on a table to describe the three states of matter but was unable to complete the work:

Complete the notes for 1 to 4 using the statements below: [3 marks]

 Quite close together Vibrating about a fixed point Moving very fast Quite far apart

1 - Vibrating about a fixed point

2 - Quite close together

3 - Moving very fast

4 - Quite far apart

There are only three marks available in questions like this because if you get the first three right, the fourth is bound to be correct.

## Sample question 2 - Higher

Question

a) Ice melts when it is heated. Explain what happens to the water molecules when an ice cube melts. [2 marks]

b) Solid carbon dioxide is called dry ice. Normally dry ice sublimes as it warms up. Explain the difference between melting and subliming. [2 marks]

a) As the molecules gain energy they vibrate more. Eventually they will gain enough energy to be able to move between each other and be unattached from other molecules.

b) Melting means that the substance changes from the solid state to the liquid state.

Subliming means the substance changes from the solid state directly into the gas state.

## Sample question 3 - Higher

Question

This table shows the density of three different metals:

MaterialDensity (g/cm³)
Aluminium2.7
Iron7.9

Use the formula for density to answer the following questions about the metals:

a) What is the volume of a 30 g lead fishing sinker?

b) What is the mass, in kg, of an 800 cm3 iron cannon ball?

c) A metal statue has a volume of 2,000 cm3 and a mass of 15.8 kg. Which metal is used to make the statue? [4 marks]

a) Density = mass ÷ volume

Volume = mass ÷ density = 30 ÷ 11.3 = 2.65 cm3

b) Mass = density × volume = 7.9 × 800 = 6,320 g = 6.32 kg

c) 15.8 kg = 15,800 g

Density = mass ÷ volume = 15,800 ÷ 2,000 = 7.9 g/cm3

It is an iron statue.