Explain the term greenhouse effect. What are its benefits? How is it harmful?

State three ways by which carbon dioxide gas is added into the atmosphere.

Fill in the blanks:

(a) …………… is formed when carbon is burnt in a limited supply of air or oxygen.

(b) Carbon monoxide burns in air with a …………… flame to form carbon dioxide.

(c) Carbon monoxide is a product of …………… combustion.

(d) A mixture of 95% oxygen and 5% carbon dioxide is called ……………

(e) Carbon monoxide is used as a …………… in the extraction of pure metals from their corresponding ores.

Assertion (A): Carbon can form a large number of compounds, most of which are studied under organic chemistry.

Reason (R): Carbon atoms can form long chains with each other.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.