Question:medium
Most diffusible ion across the cell membrane is?
Most diffusible ion across the cell membrane is?
Show Hint
Compare the cations with the chief diffusible anion of the body.
Updated On: Jun 24, 2026
- Na+
- K+
- Cl-
- None
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Diffusion across the membrane depends on how well a solute dissolves in the fatty interior of the bilayer. The better the lipid solubility, the higher the permeability.
Step 2: Ions face a barrier because of their charge and hydration shell, so all of them cross slowly compared with gases. But among ions themselves there is a ranking.
Step 3: Chloride moves through the membrane more freely than the cations sodium and potassium. Sodium is actively excluded by the Na-K pump, and potassium sits between the two. Comparing the three, chloride shows the greatest passive movement.
Step 4: So the single ion that diffuses most across the membrane is chloride.
\[\boxed{\text{Cl}^-}\]
Step 2: Ions face a barrier because of their charge and hydration shell, so all of them cross slowly compared with gases. But among ions themselves there is a ranking.
Step 3: Chloride moves through the membrane more freely than the cations sodium and potassium. Sodium is actively excluded by the Na-K pump, and potassium sits between the two. Comparing the three, chloride shows the greatest passive movement.
Step 4: So the single ion that diffuses most across the membrane is chloride.
\[\boxed{\text{Cl}^-}\]
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