In March 2015, the American space program sent astronaut Scott Kelly to live on a space station for a whole year, where he will not feel gravity as the space station orbits Earth. Scott Kelly’s twin brother, Mark, stayed at home. Scientists then plan to study the twins’ body chemistry, genetics, sight, and other data. This way, scientists can find out how living with and without gravity affects two identical people. What will most likely be a limitation for other scientists trying to recreate this study?
There are ethical controversies over testing human subjects.
There are probably very few astronauts with twin siblings.
There are too many complexities involved in studying body chemistry, genetics, and sight.
There is probably not enough technology to keep someone in space for an entire year.

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 

Hi; /c

A.(nh4)(2co3)is the correct answer