The correct answer is D. The molecular mass of a gas is not related to its vapour pressure.
Vapour pressure is the pressure exerted by a vapor in equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system. The equilibrium vapor pressure is a function of temperature, and it increases with increasing temperature.
The molecular mass of a gas is the mass of one mole of the gas. It is calculated by multiplying the atomic mass of each element in the gas by the number of atoms of that element in the molecule, and then adding the products together.
The molecular mass of a gas does not affect its vapour pressure. The vapour pressure of a gas is determined by the temperature and the intermolecular forces between the molecules of the gas.
The following is a brief explanation of each option:
- Option A: Twice its vapour pressure. This is incorrect because the molecular mass of a gas is not related to its vapour pressure.
- Option B: Equal to its vapour pressure. This is incorrect because the molecular mass of a gas is not related to its vapour pressure.
- Option C: Half its vapour pressure. This is incorrect because the molecular mass of a gas is not related to its vapour pressure.
- Option D: Not related to its vapour pressure. This is the correct answer because the molecular mass of a gas is not related to its vapour pressure.