Question

There are four conformational isomers of $n$ -butane. Eclipsed, Fully eclipsed, Gauche, Staggered
Arrange these isomers of $n$ -butane in increasing order of energy.

• A. Gauche < Eclipsed < Staggered < Fully eclipsed
• B. Staggered < Gauche < Eclipsed < Fully eclipsed
• C. Fully eclipsed < Eclipsed < Gauche < Staggered
• D. Gauche < Staggered < Eclipsed < Fully eclipsed

Answer 1

Answer: (B)

The increasing order of stability of four conformational isomers of $n$-butane is :
Fully eclipsed $<$ Partly eclipsed $<$ Gauche $<$ Staggered
$\text{Energy}\propto \frac{1}{\text{Stability}}$
Thus, order of increasing energies of isomers of $n$-butane is,
Staggered $<$ Gauche $<$ Partly eclipsed $<$ Fully eclipsed