Q.Assertion: The imbalance in concentration of Na+, K+ and proteins generates action potential. Reason: To maintain the unequal distribution of Na+ and K+, the neurons use electrical energy.
a. Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
b. Both Assertion and Reason are true but the Reason is not the correct explanations of Assertion.
c. Assertion is true, but Reason is false.
d. Both Assertion and Reason are false.

A nerve impulse is a travelling electrical signal made possible by an unequal distribution of ions across the axolemma — high K+ and negatively charged proteins inside the axon, high Na+ outside — actively maintained by the ATP-driven sodium-potassium pump (3 Na+ out for every 2 K+ in). At rest, the membrane is far more permeable to K+ than Na+, so the inside stays negative relative to the outside (typically around -70 mV); this baseline is the resting potential, and the membrane is described as polarized. A strong enough stimulus opens voltage-gated Na+ channels, letting Na+ rush in and flip the membrane's charge — depolarization — and once this reaches the threshold potential (~-55 mV) the neuron fires completely (the all-or-none principle), spiking to roughly +45 mV. The Na+ gate then closes and the K+ gate opens, letting K+ flow back out and pulling the potential back down — repolarization — and because the K+ gates ('lazy gates') close slowly, the potential often b …