Explanation:

* Reactivity: Calcium is more reactive than magnesium. This is due to its larger atomic size and lower ionization energy, which makes it easier for calcium to lose electrons and form cations.

* Electropositivity: Calcium is more electropositive than magnesium, meaning it has a greater tendency to lose electrons. This increased electropositivity enhances its reactivity with CO2.

* Oxidation Potential: Calcium has a higher oxidation potential than magnesium, indicating its greater tendency to be oxidized.

Reaction with CO2:

Both magnesium and calcium react with CO2 to form carbonates:

Mg + CO2 → MgCO3

Ca + CO2 → CaCO3

However, the reaction rate is significantly faster for calcium due to its higher reactivity.

Additional Factors:

* Surface Area: A larger surface area of the metal will result in a faster reaction rate.

* Temperature: Increasing the temperature will generally increase the reaction rate.

* Presence of Water: Water can act as a catalyst and accelerate the reaction rate.

Conclusion:

Calcium reacts faster with CO2 than magnesium due to its higher reactivity, electropositivity, and oxidation potential. The reaction rate can be influenced by factors such as surface area, temperature, and the presence of water.