For visual sense,the nerve impulse is generated by

Which of the following statements is/are correct?
$(a)$ The electrical potential difference across the resting plasma membrane is called the resting potential.
$(b)$ $Na^+$ ions are responsible for the generation of an action potential.
$(c)$ $A$ nerve impulse is an action potential.

For the maintenance of ionic gradients across the resting membrane,the sodium-potassium pump transports:

Select the correct sequence of statements regarding the conduction of a nerve impulse and select the correct option given below.
$i.$ Rapid influx of $Na^{+}$ inside the axon.
$ii.$ $Na^{+}$ gates are closed and $K^{+}$ gates open after the refractory period.
$iii.$ Intracellular fluid is electronegative and the potential difference is $-70 \ mV$.
$iv.$ Extracellular fluid becomes electronegative.
$v.$ Disturbance to the resting potential.

The velocity of a nerve impulse is greater in:

Identify the incorrect statement.