Which of the figures given below represents a NOR gate?

Question

Question

This question was previously asked in

URSC ISRO Technical Assistant Electronics 13 November 2016 Official Paper

Answer 1

The IEEE/ANSI standard for logic symbols uses rectangular symbols to represent all logic gates and circuits.
The figure below shows the IEEE/ANSI symbols alongside the traditional symbols for the basic gates:

Observations:

The rectangular symbols use a small right triangle in place of the small bubble of the traditional symbols to indicate the inversion of the logic level.
A special notation inside each rectangular symbol describes the logic relation between inputs and output.
The "1" inside the INVERTER symbol denotes a device with only one input.
The "&" inside the AND symbol means that the output will go high when all the inputs are high.
The "≥" inside the OR gate means that the output will go to HIGH whenever one or more inputs are HIGH.