Question

What is the resistance of an ideal conductor?
how does the resistance vary if the length of a conductor is doubled?

Answer 1

Resistance of a conductor is the difficulty measured by the electron to pass through a cross-sectional area of the conductor.
For an ideal conductor, when conduction is infinite, resistance approaches 0.

According to relation $R=p \frac{L}{A}$ (where p is the density of the conductor),
With increase in length, resistance increases.
Therefore with length doubled, resistance will be doubled.