The membrane is permeable to the non-polar molecules like CO2.
Sodium also can diffuse through the membrane but it needs channels (or transmembrane transporters). the same thing for the glucose and the starch (these transporters can transport molecules passively or actively).
But the CO2 can pass the plasmic membrane easily without channels because it is partially water-soluble, and it is non-polar, so it has no charges, and can pass through the amphiphile phospholipid molecules.
