Final answer:
Hydrogen gas (H₂) will have the lowest density at a specified temperature and pressure among the given options because it has the lowest molar mass.
Step-by-step explanation:
The question asks which gas will have the lowest density at a specified temperature and pressure. The density of a gas can be determined by its molar mass at a given temperature and pressure because, according to the ideal gas law (PV=nRT), the volume of gas is dependent on the number of moles and the temperature and pressure conditions, but not on the identity of the gas.
- H₂: Molar mass = 2.02 g/mol
- CClF₃: Molar mass = 104.46 g/mol
- CO₂: Molar mass = 44.01 g/mol
- C₂H₆: Molar mass = 30.07 g/mol
Since hydrogen gas (H₂) has the lowest molar mass listed it will have the lowest density at the same temperature and pressure compared to CClF₃, CO₂, and C₂H₆.