Why is resistance more in series combination of resistors ?

In series combination of resistances :

Why is resistance less in parallel combination of resistors ?

(a) Why does resistance increase in a series combination of resistors ? (b) Why does resistance decrease in a parallel combination of resistors ?

Derive the formula of equivalent resistance of series combination of resistors.

Derive the formula of equivalent resistance of series combination of resistors.

What is Ohm's law ? How is it represented graphically ? Derive an expression for the resultant resistance of a series combination of resistors.

The equivalent resistance of a series combination of two resistors is '9 Omega' and the equivalent resistance of a parallel combination of the same two resistors is 2 Omega . Find the resistances of the resistors.

The resistance of series combination of 2 resistors is S. When they are joined in parallel the total resistance is P. If S = nP , then minimum possible value of n is