Answer:The following statements are correct: 1,2 and 6
Explanation:
1.The cyclohexane ring adopts a chair conformation in order to minimize its torsional strain. In chair conformation 4 carbon atoms are in one plane 1 carbon atom is above that plane and the other 1 carbon atom is below that plane .This leads to chair conformation in which the bond angles are very close to the ideal tetrahedral angle of 109.5 degrees. The C-C-C bond angle in chair conformation is 110 degrees which is almost equal to the ideal tetrahedral angle.
2. In cyclohexane molecule as the molecule adopts a chair conformation in order to eliminate the torsional strain which would occur if the cyclohexane ring were to be planar. Torsional strain is basically the inter electronic repulsion between the atoms that do not share a bond. So this strain happens on account of eclipsing atoms. In case of eclipse structure there would be a lot of torsional strain. In case of chair conformation all the C-H bonds happen to be completely staggered in nature to eliminate the torsional strain.
3. The ring strain in case of cycloalkanes are dependent upon the number of CH₂ groups present as that would determine the size of the ring and subsequently its structure ,whether the ring would be 5 , 6 or 7 membered .Cyclohexane is a 6 -membered as there are 6CH₂ groups in it and the existence of chair conformation is only for Cyclohexane or for molecules having 6-membered ring . Any change in number of CH₂groups would lead to a different conformational structure.
4.All the bond angles in cyclohexane ring is approximately 110 degrees which is almost equal to the ideal terahedral bond angle. So the bond angles in cyclohexane are optimal.
5.The C-H bonds in cyclohexane are always staggered and never eclipsed in order to reduce there torsional strain.
6.All the bonds in cyclohexane ring are staggered to eliminate the torsional strain. It is quite evident that the cyclohexane ring is completely stable free of the ring strain.So there are no eclipsing bonds present in cyclohexane.
So the statements which are correct 1,2 and 6
