Question

Calcium ion combines with the bi-carbonate ion to form calcium carbonate. In the ocean most of the calcium carbonate is made by shell building organisms called calcifying organism such as corals.

Is this statement true?

• A. True
• B. False

Answer 1

The correct option is A

True

This statement is completely true. This is a part of the slow carbon cycle. Takes over 100 to 200 million years for this carbon cycle to make one full circle. Atmospheric carbon dioxide is converted into bicarbonate ions by an intermediate called carbonic acid which is formed by mixing carbon dioxide with water. This carbonic acid then dissociates into carbonate ions which precipitate into calcium carbonate which is then converted into limestone by marine organisms.