Question

Are the H2O molecules are too large to pass between the phospholipids while the molecules of CO2 and O2 are not?

Answer 1

I wouldn't call a water molecule large in relation to co2 and o2

I would call them polar, though,

Lehninger Principles of Biochemistry, 5E. Lehninger, et alia.

Lehninger Principles of Biochemistry, 5E. Lehninger, et alia.

The polarity of these molecules makes it very hard to pass through the largely hydrophobic interior of the phospholipid bilayer,