Answer:
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 nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot. A concentration gradient is a just a region of space over which the concentration of a substance changes, and substances will naturally move down their gradients, from an area of higher to an area of lower concentration.
In cells, some molecules can move down their concentration gradients by crossing the lipid portion of the membrane directly, while others must pass through membrane proteins in a process called facilitated diffusion.
Explanation:
there are your two reasons molecules cannot pass easily through the cell membrane and what part of the cell membrane helps them get through is concentration gradient
Answer:slowly
Explanation: when a gas is being cooled then its particles are gonna slowly stop moving to form a liquid
Answer: The octet rule is a chemical rule of thumb that reflects the observation that main group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.
Explanation:
