Prabin Kalikote

a.    Methane.            
       It occurs in gaseous state at room temperature.
       Its two uses are:
    > It is used in laboratory.
    > It is used to make printing ink and paints.
b.    Ethane.            
       It occurs in natural gas and petroleum mines.
 ...

The group organic compounds having similar structure and chemical properties in which the successive compounds differ by - CH₂ group is called homologous series.
The first five members are:
    Methane ( CH₄ )        
    Ethane ( C₂H₆ )        
    Propane ( C₃H₈ )        
    Butane ( C₄H₁₀...

a.    Saturated hydrocarbon having three carbon atoms.
       Name: Propane             
       Formula: C₃H₈
b.    An alkene having four carbon atoms.
       Name: Butene              
       Formula: C₄H₈
c.    An alkyne having two carbon atoms.
       Name: Ethyne       ...

A functional group is an atom or group of atoms that determines the chemical properties of a hydrocarbons.
For example:
                Ether ( - 0 - )
                Aldehyde ( - CHO )

The unsaturated hydrocarbons in which any two carbon atoms are connected by a double covalent bond are called alkenes.
Eg.      (ene groups)
            Methene, Ethene, etc.
The unsaturated hydrocarbons in which any two carbon atoms are connected by a triple covalent bond are called alkynes.
Eg.     (ene groups)
           Methyne, Ethyne, etc.

The saturated hydrocarbons in which all carbon atoms are connected by a single covalent bond is called alkanes.
Any three examples are:
    Methane (CH₄)
    Ethane (C₂H₆)
    Pentane (C₅H₁₂)

Hydrocarbons in which carbon atoms are connected by a single covalent bond are called saturated hydrocarbons.
For eg.    Methane, ethane, propane, etc.
Hydrocarbons in which carbon atoms are connected by the multiple covalent bond are called unsaturated hydrocarbons.
Foe eg.    Ethene, ethyne.