Name three factors on which resistance of a given wire depends and state how it is affected by the factors stated by you?

How does the resistance of a wire depend on it's length ? Give a reason for your answer.

Figure below shows the I-V curves for two resistors. Identify the ohmic and non-ohmic resistors. Give a reason for your answer.

Two wires, one of copper and other of iron, are of the same length and same radius. Which will have more resistance? Give reason.