The air in an inflated balloon (the system) absorbs 125 j of heat from its proximity to a fire. the balloon expands and does 85 kj of work. what is the change in internal energy (in kj) (δu) for the system? round to the nearest whole number. do not include units.

Given:
Q = 125 J, heat absorbed
W = 85 kJ, work done

According to the 1st law of thermodynamics, the change in internal energy is
ΔU = Q - W 
      = 0.125 kJ - 85 kJ
      = - 84.9

 - 85 (nearest integer)

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