Which of the following statements about a molar solution is correct? it

Analyze the question: You are asked what defines a molar solution.

Concept: A molar solution (1 M) is a solution with a concentration of 1 mole of solute per 1 dm³ (1 litre) of solution. Concentration (molarity) is given by:

Molarity = number of moles of solute ÷ volume of solution (dm³)

So a 1 M solution has 1 mol/dm³.

Checking each option:

• A. Supersaturated solution: Incorrect. Supersaturation is about holding more solute than normal solubility allows at a given temperature. It has nothing to do with molarity.
• B. Cannot dissolve more solute at that temperature: Incorrect. This describes a saturated solution. A molar solution can often still dissolve more solute (for example, 1 M NaCl is well below saturation, since NaCl dissolves up to about 6 M).
• C. Contains any amount of solute in a given volume: Incorrect. Molarity is a specific, fixed concentration, not "any amount."
• D. Contains one mole of the solute in 1 dm³ of solution: Correct. This is exactly the definition of a molar solution.

Example: To make 1 M NaOH, dissolve 40 g of NaOH (molar mass = 40 g/mol) in water and make the solution up to 1 dm³.

Exam tip: Do not confuse the terms:

• Molar = 1 mole per dm³ (concentration)
• Saturated = no more solute can dissolve (solubility limit)
• Supersaturated = holds more than the saturation amount