When hydrochloric acid is dripped onto marble, bubbling is observed while dripping hydrochloric acid onto granite does not lead to bubbling. Based on these observations, what compound may be a component of marble but not granite?

Calcium carbonate

Explanation:

Marble is mainly composed of calcium carbonate.

When hydrochloric acid is dipped on the marble a reaction occurs between the carbonate group of the calcium carbonate and hydrochloric acid which results in the formation of carbon dioxide. The bubble which are seen are of this carbon dioxide gas.

Granite is mainly composed of quatrz and feldspar and no carbonate is found in the granite that's why there are no bubbles of carbon dioxide released when hydrochloric acid is dropped on to the granite.