Question

A sample of oxygen gas is sealed in container X. A sample of hydrogen gas is sealed in container Z. Both samples have the same volume, temperature,

and pressure. Which statement is true?
(1) Container X contains more gas molecules than container Z.
(2) Container X contains fewer gas molecules than container Z.
(3) Containers X and Z both contain the same number of gas molecules.
(4) Containers X and Z both contain the same mass of gas.

Answer 1

(3) Containers X and Z both contain the same number of gas molecules is your answer. Following Avogadro's law, under the same temperature and pressure, the number of gas molecules is directly proportional to the volume of the gas. Equal volume under the same conditions means equal number of gas molecules.