Matching molar concentrations of solutions Steps:

• Calculate moles of NaOH in Q: molar mass of NaOH is 40 g/mol, so moles = 40 g / 40 g/mol = 1 mol.
• Convert Q's volume to dm³: 500 cm³ = 0.5 dm³.
• Determine Q's concentration: moles / volume = 1 mol / 0.5 dm³ = 2 mol/dm³.
• Identify option with matching concentration of 2 mol/dm³ by calculating each: moles / volume in dm³.

Why C is correct:

• Molarity = moles of solute / volume in dm³; for C, 0.5 mol H₂SO₄ / 0.25 dm³ = 2 mol/dm³, matching Q by definition of molar concentration.

Why the others are wrong:

• A: 0.2 mol / 0.25 dm³ = 0.8 mol/dm³, not equal to 2 mol/dm³.
• B: 0.25 mol / 0.1 dm³ = 2.5 mol/dm³, not equal to 2 mol/dm³.
• D: 0.1 mol / 1 dm³ = 0.1 mol/dm³, not equal to 2 mol/dm³.

Final answer: C