For which nuclear power problem do we not yet have a workable solution? a. finding a substitute for uranium once it is used up b. safe disposal of hlrw c. producing steam to turn the turbine that is not radioactive d. controlling the fission reaction

 The correct answer is B.
Safe disposal of HLRW is the nuclear power problem which we do not yet have a workable solution or may be called high-level radioactive waste which is the very difficult problem. Nuclear power was a major world energy source which was very strong in the year 1950s but from that time it has faded.

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