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.
.1
Which sample is impure?
[1 mark]
.2
Give the meaning of a pure substance in chemistry.
[1 mark]
.3
Which of these is a formulation?
[1 mark]
3 marksFoundation
Spec and skills
Original practice question
Answer and supported method checks
Acids react with metals, bases and carbonates to make salts.
.1
Name the salt made when magnesium oxide reacts with hydrochloric acid.
[1 mark]
.2
Name the salt made when sodium hydroxide reacts with sulfuric acid.
[1 mark]
.3
Name the gas produced when calcium carbonate reacts with hydrochloric acid.
[1 mark]
4 marksFoundation
Spec and skills
Original practice question
Answer and supported method checks
Some substances are listed below.
Copper, carbon dioxide, air, sodium chloride.
.1
Which substance is an element?
[1 mark]
.2
Which substance is a mixture?
[1 mark]
.3
Give the number of different elements in the formula CaCO3.
[1 mark]
.4
A student has a mixture of sand and water. Choose the best method to get the sand.
[1 mark]
3 marksFoundation
Spec and skills
Original practice question
Answer and supported method checks
The table shows the melting and boiling points of four substances.
Table: A melts at minus 95 and boils at 69 degrees Celsius; B melts at 1085 and boils at 2562; C melts at minus 210 and boils at minus 196; D melts at 44 and boils at 280.
Substance
Melting point in °C
Boiling point in °C
A
−95
69
B
1085
2562
C
−210
−196
D
44
280
.1
Which substance is a gas at 20 °C?
[1 mark]
.2
Which substance is a liquid at 75 °C?
[1 mark]
.3
Give the state symbol for a substance dissolved in water.
[1 mark]
4 marksFoundation
Spec and skills
Original practice question
Answer and supported method checks
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.
.1
Describe what happens to the electrons when magnesium reacts with oxygen.
[2 marks]
.2
What are the charges on the ions in magnesium oxide?
[1 mark]
.3
Name the type of force that holds the ions together.
