i. Draw the conformation of cyclobutane that can overcome the eclipsing strain.
ii. Draw the puckered conformation of cyclobutane in Newman projection.

Explanation

i.
Cyclobutane is not a flate ring but exists in two puckered ('folded') conformation structures in equilibrium, in which eclipsing is eliminated and replaced by staggered H atoms. Puckering offsest the slight increase in angle strain because the new angles are `88^(@)`. The four circled H atoms in (I) are in axial position and altrnate between up and down, and the other four H atoms projecting outward from the permeter of the ring, are in equatorial position. Similarly, the four boxed H atoms in (II) are in equatorial position and alternate between up and down, and the other four H atoms projecting inward in the perimeter of the ring are in axial position.
ii. Newman projection of puckered conformation of cyclobutane.