Identify the equivalent logic gate represented by the given circuit

The incorrect statement about the property of a Zener diode is :

The collector current in a common base amplifier using n-p-n transistor is 24 mA. If 80% of the electrons released by the emitter is accepted by the collector, then the base current is numerically :

In the given circuits (a), (b) and (c), the potential drop across the two p-n junctions are equal in