Question

(a) What are hydrocarbons ? Explain with examples.

(b) Explain the meaning of saturated and unsaturated hydrocarbons with two examples each.

(c) Give the names and structural formulae of one saturated cyclic hydrocarbon and one unsaturated cyclic hydrocarbon.

(d) Give one example of a hydrocarbon, other than pentane, having more than three isomers.

Answer 1

(a) A compound made up of hydrogen and carbon only is called a hydrocarbon (Hydrogen + Carbon= Hydrocarbon). For exampe: methane (CH₄ ), ethane (C₂H₆), ethene (C₂H₄), and ethyne (C₂H₆), all are hydrocarbons as they are made up of only two elements: carbon and hydrogen.

(b) Saturated Hydrocarbons: These are the ones in which the carbon atoms are connected by only single bonds. They are also known as alkanes.

Example: Methane (CH₄) and ethane (C₂H₆)

Unsaturated Hydrocarbons: These are the ones in which two carbon atoms are connected by a double bond or a triple bond.

Example: Ethene (C₂H₄) and ethyne (C₂H₂)

(c) Saturated cyclic hydrocarbon: Cyclohexane, C6H12 Unsaturated cyclic hydrocarbon: Benzene, C6H6

(d) Hexane, C₆H₁₄