g When an oxygen molecule diffuses from the air in the lung into the plasma in a capillary in the lung, how many times does it have to diffuse through a plasma membrane before reaching the plasma

The answer is 2.

Explanation:

When oxygen gets into the lungs, it first needs to diffuse through the alveoli and into the blood. Then through the veins and capillaries, it diffuses into all the calls in the body. It does so quite easily because it is a nonpolar and a very small molecule with a low concentration inside the cell. This gives it the ability to diffuse easily through the cell membrane.

So the number of times that oxygen has to diffuse through a plasma membrane is two.

I hope this answer helps.

its temperature is increasing. this causes molecular vibrations to increase.