For which of these processes is the value of AH expected to be positive?

1. The temperature increases when calcium chloride dissolves in water.

2. Steam condenses to liquid water

3. Water boils

4. Dry ice sublimates

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 

Muscle fiber i think that i right

Answer/// polar air mass are coldforms in high latitudes earth polestropical air mass forms over an ocean and carries warm, humid airmaritime air mass forms over oceans and are humidcontinental air mass that develops over northern canada

Im pretty sure c is the correct answer