(a)
CH3CH2CH2OH
Number
of C – atoms in the longest chain is 3
Parent
alkane is Propane
Root
word Prop
Suffix
– ol
The
carbon atom to which –OH group is attached is numbered as C1
followed by other carbon atoms numbering.
∴ IUPAC name of CH3CH2CH2OH is Propan-1-ol
(b)
HCOOH:
Number
of C – atoms in the longest chain – 1
Parent
alkane – Methane
Root
word – meth
Suffix
functional group is acid – oic acid
'oic
acid' replaces 'e' of methane
∴ IUPAC name of HCOOH is
Methanoic acid.
(c)
CH3 – CH = CH - CH3
Number
of C – atoms in the longest chain – 4
Parent
alkane – Butane
Root
word – but
Suffix
– ene (in case of alkene)
∴ its a butene
The
numbering of C atom starts from the carbon atom to double bond. The position of
the double bond is between the second and third C atom of which '2' is the
least.
∴ IUPAC name of CH3
– CH = CH - CH3 is But – 2 –
ene.