Exam Questions

Question 1

Which group of elements had not been discovered when Mendeleev Periodic table was published?

Answer 1

Group 0 / Noble gases

Question 2

What is an isotope?

Answer 2

atoms with the same number of protons but with different number of neutrons.

Question 3

Acids react to produce salts.

Universal indicator is added to water and then nitric acid is added to the mixture.

Give the colour change when nitric acid is added to the mixture of
universal indicator and water

Answer 3

Green to Red

Question 4

What happens to the pH of water when nitric acid is added?

Answer 4

Decreases

Question 5

What is the state symbol for nitric acid?

Answer 5

aq

Question 6

The formula of the zinc ion is Zn2+
The formula of the nitrate ion is NO3-

What is the chemical formula for zinc nitrate?

Answer 6

Zn(NO3)2

Question 7

Acids react with insoluble metal oxides to produce salts.

Plan a method to produce a pure, dry sample of the soluble salt copper chloride from an acid and a metal oxide.
[6 marks]

Answer 7

1.react hydrochloric acid with copper oxide.

2.in a suitable container.

3.warm (hydrochloric) acid

4.add copper oxide until solid remains

5.stir

6.filter excess copper oxide

7.pour solution into a evaporating basin

8.use a water bath or electric heater

9.heat to partially evaporated

10.leave to cool / evaporate.

Question 8

Carbon can exist in a number of different structures.

The first fullerene to be discovered was Buckminsterfullerene.
What is the formula of Buckminsterfullerene?

Answer 8

C60

Question 9

Graphite is a form of carbon.

Explain why graphite conducts electricity.

Answer 9

Graphite has delocalised electrons.

so the delocalised electrons carry electrical charge through the structure.

Question 10

Steel is an alloy of iron and carbon.

Explain why steel is harder than iron (3 marks)

Answer 10

Carbon atoms have different sizes to iron atoms.

So carbon atoms distort the layers of iron atoms.

therefore layers cannot slide.

Question 11

Hydrogen gas and oxygen gas are produced when sodium sulfate solution is electrolysed.

Explain how oxygen gas is produced in the electrolysis of sodium sulfate solution (4 marks)

Answer 11

Water molecules break down to produce OH- ions.

Which are attracted to the positive electrode.

Where OH- ions lose electrons / oxidised.

Question 12

Methane, ethane, propane and butane all react with oxygen to produce carbon dioxide and water.

Suggest why a mixture of methane and oxygen does not react at room temperature.

Answer in terms of particles.
[2 marks]

Answer 12

Particles collide

but at room temperature particles dont have enough energy

Question 13

Aluminium is produced by the reduction of aluminium oxide (Al2O3).

What is meant by the term reduction?

Answer 13

loss of oxygen

Or

Al3+ gains electrons

Question 14

Oxygen is formed at the positive carbon electrodes.

Explain why the positive carbon electrodes must be continually replaced

[3 marks]

Answer 14

At high temperature.

oxygen reacts with carbon / electrode.

electrode burns / wears away.

to produce carbon dioxide.

Question 15

Suggest one limitation of using a ball and stick model for a water molecule.
[1 mark]

Answer 15

Any one from:

Not to scale

Not 3D

incorrect arrangement in space

electrons not shown

Question 16

Ice has a low melting point.

Water molecules in ice are held together by intermolecular forces.

Complete the sentence.

Ice has a low melting point because the
intermolecular forces are ___________________.

Answer 16

Weak

Question 17

What is the number of bonds formed by each carbon atom in diamond?

Answer 17

4

Question 18

Give two physical properties of diamond.
[2 marks]

Answer 18

Very hard

Very high melting point

Does not conduct electricity

Question 19

Name two other substances with giant covalent structures.
[2 marks]

Answer 19

Graphite

Silicon dioxide

Question 20

A student investigated the temperature change when magnesium was added to copper sulfate solution.

This is the method used.

1. Pour 30 cm3 of copper sulfate solution into a polystyrene cup.
2. Measure the temperature of copper sulfate solution every minute for 3 minutes.
3. Add magnesium on the fourth minute.
4. Measure the temperature of the mixture at 5 minutes and then every minute up to 14 minutes.

What is the dependent variable in this investigation?
[1 mark]

Answer 20

Temperature change

Question 21

Suggest why the copper sulfate solution was left for four minutes before adding the magnesium.
[1 mark]

Answer 21

to reach a constant temperature

Question 22

This question is about elements.

Caesium is in Group 1 of the periodic table.

Explain what happens to caesium atoms and to oxygen atoms when caesium reacts with oxygen to produce caesium oxide.

You should answer in terms of electrons.
[4 marks]

Answer 22

Caesium atom loses one electron

and oxygen atoms gain two electrons

so two caesium atoms react with one oxygen atom

to form ions with full outer shells

Question 23

Explain why caesium is more reactive than sodium.
You should answer in terms of electrons.
[4 marks]

Answer 23

Caesium has more shells

so the outer shell is further away from nucleus

so weaker attraction between nucleus and outer shell

so outer electron is more easily lost

Question 24

This question is about salts. box

Ammonium nitrate solution is produced when ammonia gas reacts with nitric acid.

Give the state symbol for ammonium nitrate solution.

Answer 24

aq

Question 25

What is the formula of nitric acid?

Answer 25

HNO3

Question 26

Ammonia gas dissolves in water to produce ammonia solution.

Ammonia solution contains hydroxide ions, OH–

A student adds universal indicator to solutions of nitric acid and ammonia.

What colour is observed in each solution?
[2 marks]

Colour in nitric acid:
Colour in ammonia solution:

Answer 26

Colour in nitric acid: Red

Colour of ammonia solution: Purple / Blue

Question 27

This question is about elements in the periodic table.

What order did scientists use to arrange elements in early periodic tables?

Answer 27

Atomic weight.

Question 28

In the early periodic tables some elements were placed in the wrong groups.

Mendeleev overcame this in his periodic table.

Give one way Mendeleev did this

Answer 28

Left gaps in the periodic table.

Question 29

This question is about electrolysis.

Some metals are extracted from molten compounds using electrolysis.

Why is electrolysis used to extract some metals?

Answer 29

Metal is too reactive to be extracted using carbon.

Question 30

Aluminium is produced by electrolysis of a molten mixture.

What two substances does the molten mixture contain?

Answer 30

Aluminium oxide and Cyrolite

Question 31

Explain why sodium is less reactive than potassium.
[4 marks]

Answer 31

Sodium has fewer shells

Outer electron is closer to the nucleus

meaning there is a greater attraction between the nucleus and outer shell

so electron is less easily lost.

Question 32

Nickel is extracted from nickel oxide from the reduction of oxygen using carbon.

How is carbon used to extract nickel from nickel oxide.

Answer 32

Nickel is less reactive then carbon so carbon displaces the nickel and removes the oxygen from the oxide leaving the nickel.

Question 33

What are the two differences between the properties of iron and sodium?

Answer 33

sodium is a non-transition metal with low melting and boiling points and is a soft metal.

Whereas iron is a transition metal with very high melting and boiling points and is a hard metal.