Flashcards for AQA GCSE Chemistry Use of amount of substance in relation to volumes of gases (chemistry only) (HT only), covering the key terms, definitions and equations you need to recall for Paper 1 and Paper 2. 20 cards drawn from Use of amount of substance in relation to volumes of gases (chemistry only) (HT only), matched to the AQA GCSE Chemistry (8462) specification. Recall questions account for roughly 40% of marks at GCSE Chemistry, so these target the marks you can secure before the paper starts.