Avalanche breakdown is due to

In the case of forward biasing of a $PN-$ junction,which one of the following figures correctly depicts the direction of flow of charge carriers?

Which of the following statements is not correct when a junction diode is in forward bias?

$A$ diode having a potential difference of $0.5\, V$ across its junction,which does not depend on the current,is connected in series with a resistance of $20\, \Omega$ across a source. If $0.1\, A$ passes through the resistance,then what is the voltage of the source (in $, V$)?

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 equivalent resistance between $A$ and $B$ will be:
$(i) V_A = -10 V, V_B = -5 V$
$(ii) V_A = -5 V, V_B = -10 V$
$(iii) V_A = -4 V, V_B = -12 V$

The ratio of the resistance of a $P-N$ junction diode in forward bias to its resistance in reverse bias is approximately: