Which pair of gases crosses the plasma membrane by simple diffusion because neither carries a charge?

1. Molecules of oxygen and carbon dioxide have no charge. 2. Uncharged molecules can slip through the hydrophobic lipid core, so these two pass by simple diffusion. 3. Sodium, potassium, calcium and chloride are ions, and their charge means they must have special means of penetrating membranes. 4. Simple sugars and amino acids also need help with transport, supplied by transmembrane proteins. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 5 "Structure and Function of Plasma Membranes", section 5.2 Passive Transport_