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Which of the following statements indicates that the law of multiple proportions is
being followed.
(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.
Option (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
is the answer.