During the conduction of a nerve impulse along a neuron,what is the nature of the electrical charge on the inner side of the plasma membrane?

Give scientific reasons:
$(1)$ In an excited nerve fibre region,a positive charge is created inside the plasma membrane.
$(2)$ In some animals,the conduction of nerve impulses is saltatory.

When a neuron is in resting state $I$ not conducting any impulse,the axonal membrane is :

An action potential in a nerve fiber is generated when the $+ve$ and $-ve$ charges on the outside and inside of the axon membrane are reversed because ...........

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 $K^{+}$.

In which state is a polarized nerve fiber found?