Final answer:
When the pressure of a gas is increased at a constant temperature, the gas molecules are forced closer together. The gas that will condense at the highest pressure is the one with the highest vapor pressure at that temperature. Water vapor has the highest vapor pressure among the given gases, so it will condense at the highest pressure. Option 4.
Step-by-step explanation:
When the pressure of a gas is increased at a constant temperature, the gas molecules are forced closer together. At some point, the intermolecular forces between the gas molecules become strong enough to cause condensation to occur. Option 4.
The gas that will condense at the highest pressure is the one with the highest vapor pressure at that temperature. Vapor pressure is the pressure exerted by the gas molecules above the liquid or solid form of the substance.
In this case, the gas with the highest pressure will be the one with the highest vapor pressure. Looking at the options given, water vapor has the highest vapor pressure of the four gases. Therefore, water vapor will condense at the highest pressure.