(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.
(e) How many isomers of the following hydrocarbons are possible?
(i) C3H8 (ii) C4H10 (iii) C5H12 (iv) C6H14
(a) A compound made up of hydrogen and carbon only is called a hydrocarbon (Hydrogen + Carbon = Hydrocarbon).
For example: methane (CH4), ethane (C2H6), ethene (C2H4), and ethyne (C2H2), 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
(e) (i) None (ii) Two (iii) Three (iv) Five