# The energy difference $( in\: Kcal\: mol^{-1})$ between the staggered and eclipsed conformations of ethane is

$\begin {array} {1 1} (1)\;2.9 & \quad (2)\;2.0 \\ (3)\;3.6 & \quad (4)\;1.5 \end {array}$

(1) 2.9