Match List I with List II
| LIST I | LIST II |
| A. Output always opposite of input | I. NOR |
| B. Output 1 only when all inputs are 0 | II. NAND |
| C. Output 0 only when all inputs are 1 | III. OR |
| D. Output 1 when all inputs are 1 | IV. NOT |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-IV, B-I, C-II, D-III
A logic gate is described by its truth table: the output for every combination of inputs.
A. Output always opposite of input — this matches IV. NOT. The NOT gate has one input and inverts it: \( Y = \bar{A} \).
B. Output 1 only when all inputs are 0 — this matches I. NOR. NOR is OR followed by NOT, \( Y = \overline{A + B} \); OR gives 0 only when all inputs are 0, so NOR gives 1 only in that case.
C. Output 0 only when all inputs are 1 — this matches II. NAND. NAND is AND followed by NOT, \( Y = \overline{A \cdot B} \); AND gives 1 only when all inputs are 1, so NAND gives 0 only in that case.
D. Output 1 when all inputs are 1 — this matches III. OR. The OR gate gives 1 when at least one input is 1, so it gives 1 when all the inputs are 1.
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 – “… (i) NOT gate This is the most basic gate, with one input and one output. It produces a ‘1’ output if the input is ‘0’ and vice-versa. That is, it produces an inverted version of the input at its output.”
Logic Gates – “… The output Y is 1 when either input A or input B or both are 1s, that is, if any of the input is high, the output is high.”
Logic Gates – “… (iv) NAND Gate This is an AND gate followed by a NOT gate. If inputs A and B are both ‘1’, the output Y is not ‘1’.”
Logic Gates – “… A NOT- operation applied after OR gate gives a NOT-OR gate (or simply NOR gate). Its output Y is ‘1’ only when both inputs A and B are ‘0’, i.e., neither one input nor the other is ‘1’.”