In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would…
In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would drive:
$\mathrm{K}^{+}$into the cell
$\mathrm{K}^{+}$and $\mathrm{Na}^{+}$out of the cell
$\mathrm{Na}^{+}$into the cell
$\mathrm{Na}^{+}$out of the cell.
Solution
In the resting nerve fibre, the cytoplasm inside the axon has a high concentration of $\mathrm{K}^{+}$and a low concentration of $\mathrm{Na}^{+}$in contrast to the fluid outside the axon. Thus, if diffusion occurs the through concentration gradient $\mathrm{Na}^{+}$enters the fibre.
Related Theory
The sodium-potassium pump is a mechanism of active transport that moves sodium ions out of cells and potassium ions into cells. The sodium-potassium pump moves both ions from areas of lower to higher concentration, using energy in ATP and carrier proteins in the cell membrane. Sodium is the principal ion in the fluid outside of cells, and potassium is the principal ion in the fluid inside of cells. These differences in concentration create an electrical gradient across the cell membrane, called resting potential.