Question 3
In activity 16.2 (ii), the glowing splint put into the tube of heated potassium permanganate burst back into flame. What does this tell us?
The right answer is the one marked above.
That oxygen gas has been given off. Oxygen supports combustion, so a dying splint relights where it is present.
Carbon dioxide does not support combustion and would have put the splint out — the exact opposite observation. The relighting is itself evidence that a reaction occurred.