Write the IUPAC name (s) and structure (s) of the simplest alkane (s) with lowest molecular mass (or the least number of C atoms) which contains `1^(@), 2^(@), 3^(@)` and `4^(@)` carbon atoms.

Explanation

Three isomers are possible by joinning three kids of C by three ways:
(I) `4^(@)rarr2^(@)rarr3^(@)` or `3^(@)rarr2^(@)rarr4^(@)` (II) `2^(@)rarr4^(@)rarr3^(@)` or `3^(@)rarr4^(@)rarr2^(@)` (III) `4^(@)rarr3^(@)rarr2^(@)` or `2^(@)rarr3^(@)rarr4^(@)`