A bottle contains carbon dioxide molecules. A sample of magnesium chloride contains and ions.
.1
Compare how bonds form in the two substances.
[3 marks].2
Explain why one magnesium atom needs two chlorine atoms to form the compound.
[2 marks]Edexcel GCSE Chemistry June 2025 Paper 1H
5 questions on this paper's topics
25:001 of 5
An aluminium ion becomes an aluminium atom at an electrode. A student says that because aluminium is a reactive metal, this must be oxidation.
.1
Evaluate this statement using electron transfer, electrode identity and charge balance.
[3 marks].2
Write the balanced half-equation for this electrode change.
[1 mark]A sample contains very long covalent molecules. It softens when heated, does not conduct electricity and becomes solid again on cooling.
Explain these observations using a polymer model.
[6 marks]A student adds an alkali gradually to an acid. The measured pH values after successive additions are 2, 4, 6, 7, 9 and 11.
.1
Describe the change and identify the neutral reading.
[2 marks].2
Explain neutralisation in terms of the reacting ions.
[2 marks]Propane burns completely in oxygen to form carbon dioxide and water. A sample uses 8.0 g oxygen and produces 6.6 g carbon dioxide and 3.6 g water. No products escape before weighing.
.1
Write the balanced equation for complete combustion of propane, C3H8.
[2 marks].2
Calculate the mass of propane that reacted.
[3 marks]