Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?
a. co2
b. h2o
c. a small, nonpolar molecule such as butane (c4h10)
d. na+
e. o2

Answer;

d. Na+

Explanation;The cell membrane's main trait is its selective permeability, which means that it allows some substances to cross it easily, but not others. Small molecules that are non-polar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot.Charged ions  such as N+ and K+ Cannot permeate the cell membrane for the since uncharged molecules repel uncharged molecules present in the membrane structure.