Q.(i) Draw Newman's projection formula for the conformers of ethane molecule.

Newman's projection shows ethane's conformers by viewing down the C–C bond; the staggered conformer, with front and back C–H bonds 60° apart, is more stable than the eclipsed conformer because it has less torsional strain.

Note on the figures: this question asks for a drawn Newman projection diagram, but no figure/diagram was supplied with this question in the source paper data, so an accurate diagram cannot be reproduced here — the geometry is instead described precisely in words below (as would be needed to draw it correctly on paper).

(i) Newman's projection formulae for the conformers of ethane

In a Newman projection, ethane (CH3–CH3) is viewed end-on along the C1–C2 bond:

• The front carbon is represented by a point (the centre), with three lines radiating from it at 120° to each other (like a Y), each representing a C–H bond of the front carbon.

• The back carbon is represented by a circle drawn around the point, with three lines starting from the edge of the circle (not the centre), also at 120° to each other, representing the C–H bonds of the back carbon.

• Eclipsed conformation: the three back C–H lines are drawn directly behind (exactly overlapping, i.e. eclipsing) the three front C–H lines, so the dihedral (torsional) angle between a front C–H and the nearest back C–H is 0°.

• Staggered conformation: the back carbon is rotated by 60° relative to the front carbon, so each back C–H line falls exactly halfway between two front C–H lines, giving a dihedral angle of 60° between nearest front and back C–H bonds.

(ii) Which conformer is more stable, and why

The staggered conformation is more stable.

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