Answer:
1. Increasing the concentration of the acid
2. Increasing the temperature
Explanation:
CaCO₃ + 2HCl ⟶ CaCl₂ + H₂O + CO₂
Increasing the concentration of the acid increases the number of hydronium ions in contact with the surface of the CaCO₃ per unit time.
Increasing the temperature increases the kinetic energy of the hydronium ions, so they hit the surface of the CaCO₃ mor frequently and with greater force.
3. is wrong. The bigger the pieces, the smaller the surface area that is available for reaction.