Same acid moles yield equal total CO2, but higher concentration speeds up the reaction rate

Steps:

• Calculate acid moles in first experiment: 100 cm³ (0.1 dm³) × 0.1 mol/dm³ = 0.01 mol.
• Second experiment: 50 cm³ (0.05 dm³) × 0.2 mol/dm³ = 0.01 mol, identical amount.
• Same carbonate amount means equal total CO2 produced in both.
• Higher acid concentration in second experiment increases reaction rate, producing steeper volume-time curve.

Why B is correct:

• B shows steeper initial slope to same final volume, as rate law states reaction rate ∝ acid concentration.

Why the others are wrong:

• A: Shows half total volume, ignoring equal moles of acid.
• C: Depicts slower rate, contradicting higher concentration effect.
• D: Indicates different final volume, violating equal reactant moles.

Final answer: B