In the pH measurement context, the statement 'If the solution is acidic, H+ ions diffuse out of the layer and a negative charge is established on the outer side of the membrane' is:

• A. False
• B. True
• C. It Depends On Membrane Type
• D. Not Enough Information

Answer: (A)

The key idea is how ions diffuse across a membrane and how that diffusion affects charge on each side. Protons (H+) move from where they are more concentrated to where they are less concentrated. If H+ diffuse out of the layer into the outer solution, the layer loses positive charge and becomes negatively charged relative to the outer solution. The outer side, having gained protons, becomes more positive.

So, in an acidic outside solution, diffusion of H+ outward would not establish a negative charge on the outer side; it would leave the layer negatively charged and the outer side more positive. That mismatch is why the statement is false. In pH contexts, what you’d expect is the side the ions leave to carry away positive charge (becoming more negative), while the side the ions enter becomes more positive.