4 marksFoundation
Some substances are listed below.
Copper, carbon dioxide, air, sodium chloride.
.1Which substance is an element?
[1 mark] .2Which substance is a mixture?
[1 mark] .3Give the number of different elements in the formula
CaCO3. .4A student has a mixture of sand and water. Choose the best method to get the sand.
[1 mark] 3 marksFoundation
Carbon has two common isotopes: carbon-12 and carbon-14. The atomic number of carbon is 6.
.1Define the term isotopes.
[1 mark] .2Give the number of neutrons in an atom of carbon-14.
[1 mark] .3Which statement about carbon-12 and carbon-14 is correct?
[1 mark] 3 marksFoundation
Diamond is used in drill bits for cutting through rock.
.1Give the number of covalent bonds each carbon atom forms in diamond.
[1 mark] .2Explain why diamond is very hard.
[2 marks] 3 marksFoundation
A student tests two samples of a white solid. The pure solid melts at 122 °C.
Sample A melts at 122 °C. Sample B melts between 115 °C and 119 °C.
.1Which sample is impure?
[1 mark] .2Give the meaning of a pure substance in chemistry.
[1 mark] .3Which of these is a formulation?
[1 mark] 4 marksFoundation
Magnesium reacts with oxygen to form magnesium oxide, an ionic compound.
The electron structure of magnesium is 2,8,2 and of oxygen is 2,6.
.1Describe what happens to the electrons when magnesium reacts with oxygen.
[2 marks] .2What are the charges on the ions in magnesium oxide?
[1 mark] .3Name the type of force that holds the ions together.
[1 mark] 