Approximately how many atoms thick is a cell membrane, assuming all atoms there average about twice the size of a hydrogen atom? Assume that a hydrogen atom is about 10-10 m big.

The cell membrane is about 37.5 and 50 atoms.

Explanation:

You need to know that cell membranes are about 7.5 and 10 nm in thickness, so if each atom is 0.2 nm (remember that 1nm = 1*10⁻⁹ m) you just need to divide 7.5 and 10 by 0.2 nm. The two answers are 37.5 and 50, so the cell membrane is about 37.5 and 50 atoms.