A gas sample in a balloon contains 4.0 moles of gas at a particular pressure, volume, and temperature. If your balloon springs a leak, and the volume decreases to 1/2 of the original amount before you can plug the leak, how many moles of gas have you lost. The temperature and pressure remain the same. A sample of o2 gas was collected over H2O in a 550ml container at 21C and at a barometric pressure of 743 torr. The vapor pressure of water is 19.0 torr at that temp. How many moles of O2 were collected?

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 

Thermohaline circulation and gyres

1.75 is the weight of one medium egg