(i) Sample of carbon dioxide taken from any source will always have carbon and oxygen in the ratio 1:2.

(ii) Carbon forms two oxides namely CO2 and CO, where masses of oxygen which combine with a fixed mass of carbon are in the simple ratio 2:1.

(iii) When magnesium burns in oxygen, the amount of magnesium taken for the reaction is equal to the amount of magnesium in magnesium oxide formed.

(iv) At constant temperature and pressure, 200 mL of hydrogen will combine with 100 mL oxygen to produce 200 mL of water vapour.

Answer:

Correct Answer: (ii) Carbon forms two oxides namely CO2 and CO, where masses of oxygen which combine with a fixed mass of carbon are in the simple ratio 2:1

Explanation: According to the law of multiple proportion, when two elements can combine to form one chemical compound, the masses of one element that combine to form a fixed mass of another element, are in the ratio of whole numbers.