Here's why:

* Acidic reactions: When acid (like hydrochloric acid) comes into contact with calcium carbonate, a chemical reaction occurs.

* Carbon dioxide production: The reaction releases carbon dioxide (CO2) gas, which is what causes the fizzing or bubbling.

* The reaction: The simplified chemical equation for the reaction is:

* CaCO3 (calcium carbonate) + 2HCl (hydrochloric acid) → CaCl2 (calcium chloride) + H2O (water) + CO2 (carbon dioxide)

Key points to remember:

* Marble is a metamorphic rock formed from limestone, which is also composed of calcium carbonate.

* Other rocks containing calcium carbonate, like limestone and chalk, will also fizz with acid.

* The fizz is a sign that the rock is reacting with the acid, indicating the presence of calcium carbonate.

Let me know if you have any other questions!