For Iron:

For Oxygen:

These are the two chemical symbols for the two elements found in Iron Oxide.
Osmosis is a special kind of diffusion where solvent particles move through a semi permeable membrane from low concentration of solute to high concentration of solute.
so it depends upon
a) how much solvent is present : More the solvent on one side of semipermeable membrane more the movement of solvent particles on the other side of membrane
1. Decreases by 4. (B)
2. The atomic number changes. (B)
3. 56/26 Fe. (C)
4. Potassium-40;t1/2=25 days. (B)
5. Takes place in the upper atmosphere. (A)