Question

Staggered conformation of ethane is $12.5\, kJ\, mol^{-1}$ more stable than the eclipsed conformation. The two conformations of ethane cannot be separated at room temperature.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (B)

If both assertion and reason are true but reason is not the correct explanation of assertion.

Answer 2

Staggered conformation is more stable because in this conformation any two hydrogen atoms on adjacent carbon atoms are as far apart as possible and the repulsion between the electron clouds of $\sigma$- bonds of two non-bonded hydrogen atoms is minimum. The energy difference of 12.55 kJ mol is not large enough to prevent rotation at room temperature as a result it is not possible to seperate the two conformations of ethane.