When forward bias is applied to a $p-n$ junction,then what happens to the potential barrier $(V_B)$ and the width $(X)$ of the depletion region?

The $I-V$ characteristics of a $p-n$ junction diode in forward bias is shown in the figure. The ratio of dynamic resistance,corresponding to forward bias voltages of $2 \; V$ and $4 \; V$ respectively,is

When a $p-n$ diode is reverse biased,then

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $A$ diode under reverse-biased condition provides very small current which is nearly independent of voltage until a critical limit at which the current increases drastically.
Reason $R$: Below the critical voltage limit, only majority charge carriers flow which increases drastically above critical voltage.

The figure shows a circuit in which three identical diodes are used. Each diode has a forward resistance of $20\,\Omega$ and an infinite backward resistance. Resistors $R_1 = R_2 = R_3 = 50\,\Omega$. The battery voltage is $6\,V$. The current through $R_3$ is.....$mA$.

If the forward voltage in a semiconductor diode is doubled,the width of the depletion layer will