Edexcel GCSE Combined Science Paper 3: Chemistry 1 Higher June 2025 question paper 1SC0/1CH

Atoms of neon are made up of subatomic particles.

Figure 1 shows some information about the subatomic particles in neon atoms.

Complete Figure 1 with the missing information.

All atoms of neon have an atomic number of 10.

Describe what information about the number of subatomic particles can be obtained from the atomic number of neon.

Explain why atoms of neon are electrically neutral.

A sample of neon contains three isotopes

90.48% of neon-20

0.27% of neon-21

9.25% of neon-22

Using this information, calculate the relative atomic mass of this sample of neon.

relative atomic mass =_........

Silver nitrate and potassium chloride are ionic compounds that are soluble in water.

When potassium chloride solution is added to a solution of silver nitrate, a white precipitate forms.

Complete the equation for this reaction, including the missing state symbol.

Give the name of the white precipitate that forms.

State and explain how the white precipitate can be separated from the reaction mixture.

Silver nitrate solution conducts electricity. Solid silver also conducts electricity.

Describe how silver nitrate solution conducts electricity and how solid silver conducts electricity.

Nitrogen, N₂, oxygen, O₂and fluorine F₂ are all gases.

Nitrogen, oxygen and fluorine are in the same period of the periodic table.

Explain, in terms of electronic configuration, in which period of the periodic table nitrogen, oxygen and fluorine are located.

Fluorine has a boiling point of –188 °C.

Explain why fluorine has a low boiling point.

A mixture of nitrogen and oxygen becomes a liquid when cooled to –200 °C.

Which row shows the changes in energy and movement of the molecules as they are cooled from room temperature to –200 °C?

The mixture of liquid nitrogen and liquid oxygen can be separated.

Which process could be used to separate a mixture of liquid nitrogen and liquid oxygen?

At high temperatures, nitrogen, N₂, can react with oxygen, O₂, to form nitrogen dioxide only.

Write the balanced equation for this reaction.

Malachite, Cu₂CO₃(OH)₂, is a mineral containing copper.

When heated, malachite decomposes to form copper oxide, carbon dioxide and water.

Which apparatus should be used to heat the malachite and test for carbon dioxide?

When carbon dioxide is bubbled through limewater, a precipitate forms. This precipitate solid makes the limewater cloudy.

Name the precipitate that makes the limewater cloudy.

The equation for the decomposition of malachite when it is heated is

Calculate the maximum mass of copper oxide that can be formed when 22.1 g of malachite is decomposed completely.

(relative atomic masses: Cu = 63.5, O = 16.0, C = 12.0, H = 1.0)

maximum mass of CuO =_........

Copper can be extracted from copper oxide by heating the copper oxide with carbon.

A student investigated two methods to extract the maximum mass of copper from copper oxide.

Figure 2 shows the two methods.

Comment on the strengths and weaknesses of these two methods.

Magnesium sulfate is an ionic compound.

A student adds magnesium sulfate to water to form a solution.

Which of these will also form a solution when added to water?

Calculate the percentage by mass of oxygen in magnesium sulfate, MgSO₄.

(relative atomic mass: O = 16.0 relative formula mass: MgSO₄ = 120)

Give your answer to 3 significant figures.

percentage by mass =_........

Calculate the number of oxygen atoms in 7.20 g of MgSO₄.

(relative formula mass: MgSO₄ = 120 Avogadro constant = 6.02 × 10²³)

number of oxygen atoms =_........

*(c) Magnesium sulfate solution can be electrolysed using the apparatus shown in Figure 3.

Explain how the products are formed at the electrodes in terms of

• the ions present in the solution

• the oxidation and reduction reactions that take place at the electrodes.

You should include ionic equations as part of your answer.

This question is about ammonia.

Ammonia is a gas.

Suggest why the litmus paper used to test for ammonia gas has to be damp.

Ammonia can be made on an industrial scale using the Haber process.

The equation for the reaction is

The reaction can reach a dynamic equilibrium.

Explain what happens when the reaction reaches dynamic equilibrium.

Figure 4 shows the changes in percentage yield of ammonia at equilibrium as temperature increases, at a pressure of 300 atmospheres and at a pressure of 1000 atmospheres.

Which row of the table will give the highest percentage yield of ammonia at equilibrium?

In industry, a pressure of 200 atmospheres is used for the Haber process.

Using Figure 4, explain what happens to the position of dynamic equilibrium if the process is carried out at 100 atmospheres.

Ammonia can also be made by heating ammonium chloride.

A sample of solid ammonium chloride is heated in a boiling tube.

After a few minutes ammonium chloride, a white solid, is also seen at the top of the boiling tube, as shown in Figure 5.

Explain how ammonium chloride is formed at the top of the boiling tube.