Which graph represents the variation of charge density with distance across a $P-N$ junction?

$A$ semiconductor device $X$ is connected in series with a battery and a resistor. $A$ current of $10 \ mA$ is found to pass through the circuit. If the terminals of $X$ are connected in reverse,the current drops to almost zero. $X$ may be

The circuit shown in the following figure contains two diodes $D_1$ and $D_2$,each with a forward resistance of $50 \, \Omega$ and infinite backward resistance. If the battery voltage is $6 \, V$,the current through the $100 \, \Omega$ resistance (in amperes) is:

In the following circuit,$PN$-junction diodes $D_1, D_2$,and $D_3$ are ideal. For the following potentials of $A$ and $B$,the correct increasing order of resistance between $A$ and $B$ will be:
$(i) V_A = -10\,V, V_B = -5\,V$
$(ii) V_A = -4\,V, V_B = -12\,V$

In the given figure,which of the diodes are forward biased?

The resistance of a reverse biased $P-N$ junction diode is about