(N/A) In alkanes,the $C-C$ bond is represented by the sawhorse projection as follows:
$(i)$ In this projection,the molecule is viewed along the molecular axis. It is then projected on paper by drawing the central $C-C$ bond as a somewhat longer straight line.
$(ii)$ The upper end of the line is slightly tilted towards the right or left-hand side.
$(iii)$ The front carbon is shown at the lower end of the line,whereas the rear carbon is shown at the upper end.
$(iv)$ Each carbon has three lines attached to it,corresponding to three hydrogen atoms.
$(v)$ The lines are inclined at an angle of $120^{\circ}$ to each other.
$(vi)$ Sawhorse projections of eclipsed and staggered conformations of ethane are shown below:
$923$-s104