What is the speed of nerve impulse conduction in mammalian nerve fibers?

In a neuron,the absence of which of the following is observed in response to different types of stimuli?

During the nerve impulse (action potential),which ion has the highest permeability in the membrane?

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.

When an impulse passes,the membrane is depolarized and the charge of the cells is

During the depolarization of the nerve membrane,the nerve behavior is characterized by: