What is the nature of the reversal potential in a neuron?

$A$: In the nervous system,the generation of an action potential depends upon the influx of sodium ions into the axoplasm.
$R$: The influx of sodium ions during nerve impulse generation is due to the efflux of potassium ions.

Which of the following statement/s is/are correct with respect to generation and conduction of nerve impulse?
i. The resting potential difference is $-70 \text{ mV}$.
ii. The voltage-gated $Na^{+}$ and $K^{+}$ channels operate together and are self-closing.
iii. At the peak of action potential,the potential difference rises to $+30$ to $+60 \text{ mV}$.
iv. In medullated nerve fibre,the action potential is conducted as a wave of membrane depolarization.
v. The resting potential is maintained by the closure of gated channels of $Na^{+}$ and $K^{+}$.

When a nerve fibre is stimulated,the inside of the membrane becomes:

What is the resting membrane potential of a neuron (in millivolts)?

Which of the following ions are required for nerve conduction?