DIGITAL ELECTRONICS

& LOGIC GATES

XII NEET
1
1. A logic circuit provides the output as per the following truth table. The expression
for the output Y is:
[NEET – 2024]
A B Y
0 0 1
(a) 𝐴 ∙ 𝐵 + 𝐴 (b) 𝐴 ∙ 𝐵 + 𝐴
0 1 0
(c) 𝐵 (d) 𝐵
1 0 1
1 1 0

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2. The output Y of the given logic gate is similar to the output of a/an

[NEET – 2024]
(a) NAND gate (b) NOR gate
(c) OR gate (d) AND gate

3
3. Identify the correct truth table for the logic circuit shown below:

(a) A B Y (b) A B Y
[NEET – 2023]
0 0 1 0 0 0
0 1 0 0 1 0
1 0 1 1 0 0
1 1 0 1 1 1

(c) A B Y (d) A B Y
0 0 1 0 0 0
0 1 1 0 1 1
1 0 1 1 0 1
1 1 0 1 1 1

4
4. Identify the correct truth table for the logic circuit shown below:

(a) A B C (b) A B C
[NEET – 2022]
0 0 0 0 0 1
0 1 1 0 1 0
1 0 1 1 0 0
1 1 0 1 1 1

(c) A B C (d) A B C
0 0 1 0 0 0
0 1 0 0 1 1
1 0 1 1 0 0
1 1 0 1 1 1

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5. For the given circuit, the input digital signal are applied at the terminals A, B and C.
What would be the output of the terminal y? [NEET – 2021]

6
6. Identify the correct truth table for the logic circuit shown below:

(a) A B C (b) A B C
[NEET – 2020]
0 0 0 0 0 0
0 1 0 0 1 1
1 0 0 1 0 1
1 1 1 1 1 1

(c) A B C (d) A B C
0 0 1 0 0 1
0 1 1 0 1 0
1 0 1 1 0 0
1 1 0 1 1 0

7
7. The correct Boolean operation represented by the circuit diagram drawn is:
[NEET – 2019]
(a) NOR (b) AND
(c) OR (d) NAND

8
8. In the combination of following gates the output Y can be written in terms of input
A and B as:
[NEET – 2018]

(a) 𝐴 ∙ 𝐵 (b) 𝐴 ∙ 𝐵 + 𝐴 ⋅ 𝐵
(c)𝐴 ∙ 𝐵 + 𝐴 ⋅ 𝐵 (d) 𝐴 + 𝐵

9
9. To get the output 1 for following circuit, the correct choice for input is:
[NEET – 2010/12]
(a) A = 1, B = 1, C = 0
(b) A = 1, B = 0, C = 1
(c) A = 0, B = 1, C = 0
(d) A = 1, B = 0, C = 0

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10. The following figure shows a logic gate circuit with two inputs A and B and the
output Y. The voltage waveform of A, B and Y are as given. The logic gate is:
[NEET – 2010]
(a) NOR gate
(b) OR gate
(c) AND gate
(d) NAND gate

11
11. The following figure shows a logic gate circuit with two inputs A and B and the
output C. The voltage waveform of A, B and C are as given. The logic gate is:
[NEET – 2006]
(a) NOR gate
(b) OR gate
(c) AND gate
(d) NAND gate

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12. Which of the following logic gates will have output 1 for the inputs shown?

(a) (b)
[NEET – 1998]

(c) (d)

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13. Identify the correct truth table for the logic circuit shown below:

(a) A B Y (b) A B Y
[JEE MAIN– 2021]
0 0 1 0 0 0
0 1 0 0 1 1
1 0 1 1 0 0
1 1 0 1 1 1

(c) A B Y (d) A B Y
0 0 1 0 0 0
0 1 0 0 1 1
1 0 0 1 0 1
1 1 1 1 1 0

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14. Identify the correct output signal Y in the given combinations of gates (as shown)
for the given inputs A and B.
[JEE MAIN - 2020]
(a) (b)

(c) (d)

15
15. A proper combination of 3 NOT and 1 NAND gates is shown. If A = 0, B = 1, C = 1,
then the output of this combination is
[AIIMS – 2017]
(a) 1
(b) 0
(c) not predictable
(d) none of these

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16. The minimum number of NAND gates required for obtaining an output of
AB + CD is:

(a) 3 (b) 4 (c) 2 (d) 5 [AIIMS – 2018]

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