Reaction rate increases with surface area and acid amount

Steps:

• Reaction: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂; rate depends on surface area for collisions and HCl availability.
• Powdered CaCO₃ exposes more surface than lumps, accelerating reaction per collision theory.
• 2 ml HCl supplies more reactant than 1 ml, preventing early depletion and sustaining high rate.
• D combines maximum surface area and acid, producing CO₂ fastest to fill syringe.

Why D is correct:

• Maximizes rate via increased collisions (surface area) and reactant moles, per rate law factors in collision theory.

Why the others are wrong:

• A: Low surface area of lumps limits collisions; 1 ml acid depletes quickly.
• B: Lumps' low surface area slows rate despite 2 ml acid.
• C: High surface area, but 1 ml acid limits total HCl, slowing after partial reaction.

Final answer: D