When the $P$ end of a $P-N$ junction is connected to the negative terminal of the battery and the $N$ end to the positive terminal of the battery,then the $P-N$ junction behaves like:

The $\text{I-V}$ characteristic of a $\text{P-N}$ junction in forward bias is shown. The approximate forward resistance of the junction is $-$ (in $\Omega$)

Which one of the following statements is not correct?

In a $PN-$ junction diode not connected to any circuit:

Find $V_{AB}$ in the given circuit.

$A$ $2\,V$ battery forward biases a diode. There is a drop of $0.5\,V$ across the diode which is independent of current. Also,a current greater than $10\,mA$ produces large joule heat and damages the diode. If the diode is to be operated at $5\,mA$,the series resistance to be used is: