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(a) Four samples of carbon dioxide (CO(2...

(a) Four samples of carbon dioxide `(CO_(2))` were prepared by using different methods. Each sample on analysis was found to contain 27.27% carbon by mass. Name the law which is in agreement with this observation.
(b) Explain why the number of atoms in one mole of hydrogen gas is double the number of atoms in one mole of helium gas.

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Carbon dioxide consists of elements carbon and oxygen. Since the percentage of carbon in each sample is fixed, that of oxygen must be also fixed. This is according to law of constant proportions.
(b) Hydrogen gas is diatomic in nature `(H_(2))` while helium gas is monoatomic (He). As a result, the number of atoms in one mole of hydrogen. `(2xxN_(A))` are expected to be double as compared to number of atoms in one mole of helium `(N_(A))`.
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