Question

1. what is the main component of limestone? aluminum silicate magnesium oxide silicon dioxide calcium carbonate

Explanation:

Limestone is a sedimentary rock, and its main component is calcium carbonate ($CaCO_3$). Aluminum silicate is common in clays and some rocks, magnesium oxide is an important compound in various industrial applications but not in limestone, and silicon dioxide is a major component of sand and quartz - containing rocks.

Answer:

D. Calcium carbonate