Final answer:
The molar mass of the gas can be calculated using the ideal gas law and the given values of mass and volume. Using the molar volume of an ideal gas, we can determine the correct expression for the molar mass of the gas.
Step-by-step explanation:
The molar mass of a gas can be calculated using the ideal gas law, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin. Rearranging the equation, we have n = PV / RT. In this case, we are given the mass of the gas (3.0 grams) and the volume (1.5 liters), and we need to find the molar mass. We can express the molar mass as molar mass = mass / n. Plugging in the given values, we have molar mass = 3.0 g / (PV / RT). Given that the gas is ideal, we can use the molar volume of an ideal gas at 0°C and 1 atm, which is 22.41 L/mol. Therefore, the correct expression for the molar mass of the gas is molar mass = 3.0 g / (1.5 L / 22.41 L/mol).