Circle the Substances Below That Are Pure Elements Not Compounds

End-of-term test / Name
Form/Class

Warm-up

Circle the substances below that are pure elements not compounds.

diamond / rainwater / petrol
mineral water / nitrogen gas / gold
tin / fluoride toothpaste / glucose
table salt / iron / brass

[5]

Main test

Marks / Level
1 / Draw three molecules of oxygen gas (O2) in the box below. / [2] /
2 / Particles can be combined in different ways. Label the diagrams below as element, compound or mixture.

/ [4] /
3 / Complete the following sentences using the words below:
dissolves solute solution solvent
When sugar is added to tea, it and the tea becomes sweeter. This is an example of a . The sugar that dissolves is called the . The tea is the . / [4] /
4 / Gold, mercury, oxygen and carbon are all substances found on the Periodic Table. They all contain just one type of atom. What name do we give pure substances that contain just one type of atom? / [1] /
5 / Tick a box or box(es) to show which of the following are reversible reactions:
Melting chocolate
Frying an egg
Making a glass of orange squash
Making toast
/ [2] /
6 / A police forensics officer is investigating the ink on different forged bank notes. The experiment is shown below.

The results of the experiment are shown below, after the officer used bank notes A and B and 3 different inks X, Y and Z.

(i) What is this process of separating colours called?
(ii) The line along the bottom of the filter paper should be drawn with pencil, not with ink. Why should the line not be drawn in ink?
(iii) Use the results to identify two substances in ink A.
(iv) Draw another spot on the diagram to show what it would look like if ink B contained ink X as well. / [5] /
7 / An ice cube is taken out of the freezer and left in a warm room. The graph shows how the temperature of the cube changes.

(i) Name the process that takes place at Stage B.
(ii) Explain why the temperature stops rising at Stage D.
Four descriptions of the ways in which molecules move are given below.

They move in straight lines, colliding occasionally
They all move in the same direction at the same speed
They move past each other and are close together
They vibrate around fixed points

(iii) Choose the number of the statement that best describes the movement of the water molecules at stage A.
(iv) Choose the number of the statement that best describes the movement of the water molecules at stage C. / [4] /
8 / Another ice cube is put in a glass of water at room temperature. The ice floats on the water.
Explain why the ice floats. Make sure your answer contains the terms ‘density’, ‘molecules’ and ‘bonding’. / [2] /
9 / Air is a gas at room temperature. The chemical formulas below show some of the substances in the air.
Ar O2 Ne N2 H2O CO2
(i) For each formula decide whether it is an element or a compound. Write the formulas in the correct columns in the table below.
Elements / Compounds
(ii) Decide for each formula whether it contains atoms or molecules. Write the formulas in the correct columns in the table below.
Atoms / Molecules
/ [4] /
10 / Balloons are sometimes filled with helium so they float. The chemical symbol for helium is He.

(a) compound gas (b) element gas

(c) mixture gas
(i) Which diagram represents air?
(ii) Which diagram represents helium?
(iii) Explain why a helium balloon rises but a balloon filled with air drops to the ground. / [3] /
11 / Two beakers containing equal amounts of water are set up. One beaker is heated to 80 °C, the other is kept at room temperature (about 20 °C). A crystal of purple potassium permanganate is dropped into each beaker.

Describe and explain the outcome of the experiment. / [3] /
12 / A student heated blue copper sulphate crystals. The crystals turned into white copper sulfate. The word equation for this reaction is shown below:

(i) What does this symbol ⇋ mean?
(ii) How could the student turn the white powder back to blue crystals? / [2] /

Six-mark question

When answering this question you need to:

use good English, paying attention to spelling and punctuation
organise your information clearly with an introduction, an explanation and a conclusion
(you can use a table for the explanation if you prefer)
ensure that you use the correct scientific terms.

Read the following investigation:

A spoonful of sugar
A student is investigating what happens to sugar in water. He labels two beakers A and B and adds 150ml of warm water to each beaker. The student then measures out some sugar and a sugar cube. Both types of sugar are the same.
Into Beaker A he puts the sugar cube.
Into Beaker B he puts the sugar.

Use your understanding of particle theory to explain what happens to the sugar in both beakers.

[6]