A student burns a small piece of sulfur inside a sealed gas jar of oxygen. Sulfur dioxide is produced. What happens to the total mass of the sealed gas jar and its contents?
It increases while the sulfur is burning.
It decreases while the sulfur is burning.
It stays the same while the sulfur is burning.
It increases and then falls back to its starting value.
95 exam-style questions on AQA GCSE Chemistry 3.1 Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations, covering 3.1.1 Conservation of mass and balanced chemical equations, 3.1.2 Relative formula mass, 3.1.3 Mass changes when a reactant or product is a gas, and 3.1.4 Chemical measurements. Each one has a worked solution and a mark scheme showing where the marks go.