Final answer:
When PNa is changed to 0 and PCl is 0, the membrane potential Vm becomes more negative the cell becomes more impermeable to positive ions and more permeable to negative ions.
Step-by-step explanation:
Vm is the membrane potential, which is the electrical potential difference across the cell membrane. When PNa is changed to 0 and PCl is 0, it means that the permeability of the cell membrane to both sodium and chloride ions is reduced to zero.
This would result in the membrane potential Vm becoming more negative, as the cell becomes more impermeable to positive ions and more permeable to negative ions.