which of the following quantities is a molar quantity?

Step 1: Analyze the question The question asks which quantity is a "molar quantity." In chemistry, a molar quantity is a property expressed per mole of a substance. In other words, it is divided by the amount of substance (n).

Step 2: Explain the concept A molar quantity = (some property) ÷ (amount of substance in moles).

Examples:

• Molar mass = mass ÷ moles (g/mol)
• Molar volume = volume ÷ moles (dm³/mol)
• Molar enthalpy = enthalpy change ÷ moles (kJ/mol)

Step 3: Check each option

• A. Molarity is moles of solute per volume of solution (mol/dm³). It is a concentration, not a per-mole quantity. ✗
• B. Molar mass is mass per mole (g/mol). It is divided by the amount of substance, so it is a true molar quantity. ✓
• C. Mass concentration is mass per unit volume (g/dm³). It has no mole in its definition. ✗
• D. Molality is moles of solute per kg of solvent (mol/kg). Again, a concentration measure. ✗

Step 4: Answer The correct option is B. Molar mass.

Tip: Molarity and molality are concentrations (moles per volume or per mass of solvent). A true "molar" quantity has the mole in the denominator, as in "per mole." Ask yourself, "Is it something divided by moles?" If yes, it's molar.