Question Constellation Sign up for free AQA · GCSE · Chemistry · Higher
Hydrogen combustion reaction classification
Hydrogen gas reacts with oxygen gas to produce water. Water is decomposed into hydrogen gas and oxygen gas using electricity.
Which two words describe the reaction between hydrogen gas and oxygen gas? Tick two boxes.
Write your answer first. You can study the marking guidance whenever you need it.
Study the marking See what earns credit and compare it with a full-mark answer.
Marking points
- 1 Selects Combustion.
- 2 Selects Reversible.
Why this answer loses marks
The student chooses two categories only because water is formed.
One category comes from reaction with oxygen, while the other comes from the explicitly shown reverse process.