Question detail
For Mass changes when a reactant or product is a gas, which option best supports this Unit 4.3 objective: Explain why some reactions appear to involve a change in mass when a gas is a reactant or product?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations
Question
- A. Gas escape or uptake affects the total mass
- B. The gas changes state
- C. The gas is not measured accurately
- D. The reaction is exothermic
Answer
The correct option is Gas escape or uptake affects the total mass.
Explanation
The correct option is Gas escape or uptake affects the total mass. Gas escape or uptake affects the total mass is correct because it directly supports the approved learning objective to explain why some reactions appear to involve a change in mass when a gas is a reactant or product. The reasoning belongs to Mass changes when a reactant or product is a gas within Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, so it should not be confused with nearby quantitative ideas such as mass, moles, concentration, yield, atom economy, or gas volume unless those are named in the objective. Use the focus term gas to keep the answer aligned with AQA GCSE Chemistry 8462 Unit 4.3. The other options are weaker because they either use the wrong formula, the wrong unit, a vague relationship, or the wrong quantitative context.
Common mistake
Misunderstanding Mass Change
Students often think that mass is lost when a gas escapes during a reaction, rather than understanding that the total mass remains constant.
To fix this, students should remember that the law of conservation of mass states that no atoms are lost or created, and they should consider the mass of the gas that escapes as part of the total mass of the system. Keep the correction anchored to Mass changes when a reactant or product is a gas; check formula, substitution, calculation, final answer, and unit where relevant.
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.