Order of Sequence Events A. Third 1. Sequence of impulse is repeated along the length of the axon and consequently the impulse is conducted. B. Fourth 2. A rise in permeability to K C. Second 3. Ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump which transports 3 Na+ outwards for 2 K+ into the cell- Resting potential D. First 4. Stimulus applied, h

Step-by-step solution

When a neuron is not conducting any impulse, i.e., resting, the axonal membrane is comparatively more permeable to potassium ions (K+ ) and nearly impermeable to sodium ions (Na+). Similarly, the membrane is impermeable to negatively charged proteins present in the axoplasm. Consequently, the axoplasm inside the axon contains high concentration of K+ and negatively charged proteins and low concentration of Na+. In contrast, the fluid outside the axon contains a low concentration of K+ , a high concentration of Na+