Final answer:
The statement that the number of moles of a gas is the mass divided by the molar mass is true. The molar mass is the mass of one mole of a substance measured in grams per mole and this relationship is essential in calculations involving the ideal gas law.
Step-by-step explanation:
The statement that the number of moles of a gas (n) is equal to the mass (m) divided by the molar mass (M) is A) True. The molar mass (M) is defined as the mass of one mole of a substance, typically measured in grams per mole (g.mol-⁻¹). The equation n = m/M effectively describes the relationship between the moles (n), the mass of the gas in grams (m), and its molar mass (M). When performing calculations using the ideal gas law, which can be expressed as PV = nRT, knowing the number of moles of a gas is essential. To find molar mass from the number of moles, we can manipulate the equation to M = m/n. This is crucial in determining the amount of a gas in moles when given its mass, thereby applying the ideal gas law accurately.