Answer. The compounds in which all the four valences of carbon atoms are fully satisfied (saturated) by single bonds with other carbon and hydrogen atoms are called saturated hydrocarbons. Saturated hydrocarbons are also called alkanes.
H3C-CH3
Ethane
The compounds in which two carbon atoms are linked by a multiple bond i.e. double or a triple bond are called unsaturated hydrocarbons. The compounds in which two carbon atoms are linked by a double bond are called alkenes. For example, ethene and propene
H2C=CH2 CH3—CH=CH2
Ethene Propene
While the compounds in which two carbon atoms are linked by a triple bond are called alkynes, For example,
CH≡CH H3C-C ≡ CH
Ethyne Propyne