Do exothermic reactions obey the law of conservation of energy?

Yes. All reactions obey the law of conservation of energy.

The law states that energy cannot be gained or lost, but it can be transformed into another form. Exothermic reactions releases energy as heat.

Exothermic reaction, has less chemical energy all combustion reactions are exothermic.
 All chemical reactions obey the law of conservation of energy. The law of conservation of energy states that energy cannot be created or destroyed.

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic 

Bis the