The truth table for one of the following logic gates is given. Identify the logic gate
| Input | Output | |
| A | B | Y |
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → NAND gate
The output is 0 only when both inputs are 1, and 1 for every other input. This is the inverse of the AND output (AND gives 1 only for 1, 1).
\( \displaystyle Y = \overline{A \cdot B} \)
That is the NAND gate.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Logic Gates – “… This is an AND gate followed by a NOT gate. If inputs A and B are both ‘1’, the output Y is not ‘1’. The gate gets its name from this NOT AND behaviour.”