Question

Identify the substance in which carbon exists in the free state.

• A. Cellulose
• B. Graphite
• C. Carbon dioxide
• D. Petroleum

Answer 1

The correct option is B

Graphite

Occurrence of Carbon:

1. Carbon can exist in various forms owing to the property of its atoms to combine in different ways. Carbon is said to exist in a combined state when it is bonded with some other element other than carbon such as oxygen, and calcium in the form of carbonates.
2. Apart from the combined state, carbon also exists in the free state in nature which means without combining with any other element. In the free state, carbon is mainly found to exist in three forms: Diamond, Graphite, and Coal.

Explanation for correct option:

(B) Graphite is one of the allotropes of carbon that exists in the free state.

Explanation for incorrect options:

(A) Cellulose, a complex carbohydrate consists of hundreds or thousands of molecules of carbon, hydrogen, and oxygen atoms.

(D) Similarly, Petroleum consists mainly of hydrocarbons.

(C) Carbon dioxide, a chemical compound is formed when one atom of carbon covalently bonds with two oxygen atoms. Therefore, it is also a combined state of carbon.

Thus, option (B) is correct.