WHAT IS THE FORWARD RESISTANCE OF pn JUNCTION DIODE?

Answer 1

It is not a resistance but a non linear relationship that depends on the current through it and the size of the junction. In general though, you can expect a voltage drop of about .75 volts at a milliamp of current for a silicon diode. The current through the junction varies as an exponential of the voltage across the diode and is proportional to e ^kV where k is a constant and e is the base of the natural log and V is the voltage.