Draw the most stable chair conformation for:

a$.$ trans$-1-$methyl$-3-$propylcyclohexane

b$.$ trans$-1-$bromo$-2-$iodocyclohexane

Cyclobutane has slightly less ring strain than cyclopropane. Provide a reason for this difference.

trans$-1,3-$di$-$tert$-$butylcyclohexane is more stable in a less stable boat conformation than in one of its two chair conformations. By exploring the chair conformation, explain why this is the case.