Question

what are isomers ? give example.

Answer 1

Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. That excludes any different arrangements which are simply due to the molecule rotating as a whole, or rotating about particular bonds. ... They are not isomers. Both are butane.
Butane and isobutane have the same number of carbon (C) atoms and hydrogen (H) atoms, so their molecular formulas are the same. However, each one has a different structural formula, which shows how the atoms are arranged. So, we can say that butane and isobutane are structural isomers.