Top 50 Objective Questions on Logic gates and circuit BCA | B.Tech

1.       What is a logic gate?

·         B) A basic building block of digital circuits

2.       How many inputs does an AND gate typically have?

·         B) 2 or more

3.       What is the output of an AND gate when all inputs are 1?

·         B) 1

4.       Which gate performs the operation where the output is true if at least one input is true?

·         B) OR

5.       How many inputs and outputs does a NOT gate have?

·         A) One input and one output

6.       Which gate can be used to invert a signal?

·         C) NOT

7.       What is the output of a NAND gate when all inputs are 1?

·         A) 0

8.       The NOR gate is equivalent to which combination of gates?

·         B) OR followed by NOT

9.       Which gate is used in the construction of a half adder and full adder?

·         A) XOR

10.   The expression for a NAND gate can be represented as:

·         B) 𝐴⋅𝐵‾A⋅B

11.   Which law of Boolean Algebra states 𝐴+0=𝐴A+0=A?

·         B) Identity Law

12.   According to De Morgan's theorem, what is the equivalent of 𝐴⋅𝐵‾A⋅B?

·         A) 𝐴‾+𝐵‾A+B

13.   In Boolean Algebra, the expression 𝐴⋅𝐴‾A⋅A simplifies to:

·         B) 0

14.   A Karnaugh Map (K-map) is used for:

·         B) Simplifying Boolean expressions

15.   How many cells are there in a 3-variable K-map?

·         C) 8

16.   For a function defined as 𝐹=𝐴+𝐵‾F=A+B, which K-map cell should be filled with 1?

·         A) When A=1 and B=0

17.   In a 4-variable K-map, which minterm does the cell with subscript 12 represent?

·         D) 𝑊′𝑋′𝑌𝑍W′X′YZ

18.   The SOP form in Boolean algebra is represented by:

·         A) Sum of Products

19.   If a Boolean function is given as 𝐹=𝑚1+𝑚2F=m1+m2, how many cells in the K-map will be filled with 1?

·         B) 2

20.   Which Boolean law states 𝐴+𝐴‾=1A+A=1?

·         C) Complement Law

21.   Which of the following is not a basic logic gate?

·         A) AND

·         B) OR

·         C) NOT

·         D) XNOR

Answer: D) XNOR

22.   What is the output of an OR gate when all inputs are 0?

·         A) 0

·         B) 1

·         C) Undefined

·         D) Same as input

Answer: A) 0

23.   Which gate is known as an inverter?

·         A) AND

·         B) OR

·         C) NOT

·         D) XOR

Answer: C) NOT

24.   How many inputs does a standard XOR gate have?

·         A) 1

·         B) 2

·         C) 3

·         D) 4

Answer: B) 2

25.   Which Boolean algebra law is represented by 𝐴⋅(𝐵+𝐶)=𝐴⋅𝐵+𝐴⋅𝐶A⋅(B+C)=A⋅B+A⋅C?

·         A) Commutative Law

·         B) Associative Law

·         C) Distributive Law

·         D) Identity Law

Answer: C) Distributive Law

26.   What is the function of a NOR gate?

·         A) Outputs 1 if any input is 1

·         B) Outputs 0 if any input is 1

·         C) Inverts the input

·         D) Outputs 1 if all inputs are 1

Answer: B) Outputs 0 if any input is 1

27.   The expression 𝐴+𝐴‾⋅𝐵A+A⋅B simplifies to:

·         A) A

·         B) B

·         C) 1

·         D) A + B

Answer: D) A + B

28.   Which gate is called the universal gate?

·         A) AND

·         B) OR

·         C) NOT

·         D) NAND

Answer: D) NAND

29.   In Boolean algebra, the expression 𝐴+𝐴A+A simplifies to:

·         A) A

·         B) 0

·         C) 1

·         D) A + A

Answer: A) A

30.   What is the main advantage of using a Karnaugh map?

·         A) It simplifies the design of complex circuits

·         B) It increases the speed of digital circuits

·         C) It reduces power consumption

·         D) It increases the number of gates used

Answer: A) It simplifies the design of complex circuits

31.   A NOT gate's output is the:

·         A) Same as the input

·         B) Inverse of the input

·         C) Logical AND of the input

·         D) Logical OR of the input

Answer: B) Inverse of the input

32.   The output of an XOR gate is true when:

·         A) Both inputs are true

·         B) Both inputs are false

·         C) One input is true and the other is false

·         D) None of the above

Answer: C) One input is true and the other is false

33.   Which of the following expressions is equivalent to 𝐴⋅𝐵+𝐴⋅𝐵‾A⋅B+A⋅B?

·         A) A

·         B) B

·         C) 1

·         D) A + B

Answer: A) A

34.   In a 2-variable K-map, how many possible minterms are there?

·         A) 2

·         B) 4

·         C) 6

·         D) 8

Answer: B) 4

35.   What is the output of a NOR gate when both inputs are 1?

·         A) 0

·         B) 1

·         C) Undefined

·         D) Same as input

Answer: A) 0

36.   The expression 𝐴⋅(𝐴+𝐵)A⋅(A+B) simplifies to:

·         A) A + B

·         B) A

·         C) B

·         D) A \cdot B

Answer: B) A

37.   What does the output of a XNOR gate represent?

·         A) Logical OR

·         B) Logical AND

·         C) Equality of inputs

·         D) Inverse of XOR

Answer: C) Equality of inputs

38.   Which law of Boolean Algebra is used in the simplification of 𝐴+𝐴𝐵=𝐴A+AB=A?

·         A) Commutative Law

·         B) Associative Law

·         C) Absorption Law

·         D) Distributive Law

Answer: C) Absorption Law

39.   How many cells are there in a 4-variable K-map?

·         A) 4

·         B) 8

·         C) 12

·         D) 16

Answer: D) 16

40.   Which gate produces a 1 output only when all inputs are different?

·         A) AND

·         B) OR

·         C) XOR

·         D) XNOR

Answer: C) XOR

41.   The Boolean expression 𝐴+𝐴‾𝐵A+AB simplifies to:

·         A) B

·         B) A

·         C) A + B

·         D) 1

Answer: C) A + B

42.   In Boolean algebra, the expression 𝐴⋅𝐵‾A⋅B represents:

·         A) NOR

·         B) NAND

·         C) XOR

·         D) XNOR

Answer: B) NAND

43.   A gate with two inputs A and B gives a high output only when both inputs are different. Which gate is it?

·         A) AND

·         B) OR

·         C) XOR

·         D) NOR

Answer: C) XOR

44.   Which theorem states that 𝐴+𝐵‾=𝐴‾⋅𝐵‾A+B​=A⋅B?

·         A) Commutative

·         B) Associative

·         C) De Morgan's Theorem

·         D) Distributive

Answer: C) De Morgan's Theorem

45.   Which gate's output is 1 only when all inputs are 0?

·         A) AND

·         B) OR

·         C) NOR

·         D) NAND

Answer: C) NOR

46.   In a 3-variable K-map, how many cells are filled for the expression 𝐹=𝑚1+𝑚3F=m1+m3?

·         A) 2

·         B) 4

·         C) 6

·         D) 8

Answer: A) 2

47.   The expression 𝐴⋅𝐵+𝐴‾⋅𝐵A⋅B+A⋅B simplifies to:

·         A) A

·         B) B

·         C) A + B

·         D) A \cdot B

Answer: B) B

48.   What is the function of a buffer gate?

·         A) To invert the input

·         B) To combine multiple inputs

·         C) To isolate the input and output

·         D) To amplify the input signal

Answer: C) To isolate the input and output

49.   Which gate is equivalent to an AND gate followed by a NOT gate?

·         A) NOR

·         B) NAND

·         C) XOR

·         D) XNOR

Answer: B) NAND

50.   In Boolean algebra, the expression 𝐴⋅0A⋅0 simplifies to:

·         A) A

·         B) 0

·         C) 1

·         D) A \cdot 0

Answer: B) 0

51.   The output of a NOR gate is 1 when:

·         A) Both inputs are 1

·         B) Both inputs are 0

·         C) Any one input is 1

·         D) Any one input is 0

Answer: B) Both inputs are 0

52.   What is the simplified form of the Boolean expression 𝐴⋅𝐵+𝐴⋅𝐵‾+𝐴‾⋅𝐵A⋅B+A⋅B+A⋅B?

·         A) A + B

·         B) B

·         C) 1

·         D) A

Answer: A) A + B

53.   Which gate is used to combine multiple input signals into a single output signal?

·         A) AND

·         B) OR

·         C) NOT

·         D) XOR

Answer: B) OR

54.   A logic gate whose output is 1 when both inputs are 0 is:

·         A) NAND

·         B) NOR

·         C) XOR

·         D) XNOR

Answer: B) NOR

55.   The expression 𝐴⋅𝐴‾A⋅A simplifies to:

·         A) A

·         B) 0

·         C) 1

·         D) A \cdot \overline{A}

Answer: B) 0

56.   The function of a logic circuit can be described using a:

·         A) Truth table

·         B) Boolean equation

·         C) Karnaugh map

·         D) All of the above

Answer: D) All of the above

57.   Which Boolean expression represents a 4-variable K-map cell numbered 12?

·         A) 𝑊⋅𝑋⋅𝑌⋅𝑍W⋅X⋅Y⋅Z

·         B) 𝑊‾⋅𝑋‾⋅𝑌⋅𝑍W⋅X⋅Y⋅Z

·         C) 𝑊⋅𝑋‾⋅𝑌⋅𝑍‾W⋅X⋅Y⋅Z

·         D) 𝑊‾⋅𝑋‾⋅𝑌⋅𝑍‾W⋅X⋅Y⋅Z

Answer: B) 𝑊‾⋅𝑋‾⋅𝑌⋅𝑍W⋅X⋅Y⋅Z

58.   Which of the following is a canonical form of Boolean expression?

·         A) Sum of Products (SOP)

·         B) Product of Sums (POS)

·         C) Both A and B

·         D) Neither A nor B

Answer: C) Both A and B

59.   The output of an AND gate is 0 when:

·         A) Any one input is 0

·         B) Both inputs are 1

·         C) Both inputs are 0

·         D) None of the above

Answer: A) Any one input is 0

60.   How many inputs can a NAND gate have?

·         A) Only 2

·         B) Only 1

·         C) 2 or more

·         D) 3 or more

Answer: C) 2 or more

61.   Which Boolean law states 𝐴⋅𝐴=𝐴A⋅A=A?

·         A) Identity Law

·         B) Complement Law

·         C) Idempotent Law

·         D) Associative Law

Answer: C) Idempotent Law

62.   What is the output of a NOT gate when the input is 1?

·         A) 0

·         B) 1

·         C) Undefined

·         D) Same as input

Answer: A) 0

63.   What is the result of 𝐴‾‾A in Boolean algebra?

·         A) A

·         B) 0

·         C) 1

·         D) 𝐴‾A

Answer: A) A

64.   Which logic gate is known for performing the function of equality checking?

·         A) AND

·         B) OR

·         C) XNOR

·         D) XOR

Answer: C) XNOR

65.   Which Boolean algebra rule is illustrated by 𝐴⋅𝐵=𝐵⋅𝐴A⋅B=B⋅A?

·         A) Associative Law

·         B) Commutative Law

·         C) Distributive Law

·         D) Idempotent Law

Answer: B) Commutative Law

66.   In a 4-variable K-map, the cell corresponding to 𝑊′𝑋′𝑌′𝑍W′X′Y′Z is:

·         A) 0

·         B) 1

·         C) 8

·         D) 9

Answer: D) 9

67.   What is the simplified form of the Boolean expression 𝐴+𝐴‾𝐵A+AB?

·         A) A

·         B) B

·         C) A + B

·         D) 1

Answer: C) A + B

68.   Which gate is called a universal gate due to its ability to implement any Boolean function?

·         A) AND

·         B) OR

·         C) NAND

·         D) XOR

Answer: C) NAND

69.   A Boolean expression where each term contains all the variables exactly once is called:

·         A) Minterm

·         B) Maxterm

·         C) Canonical form

·         D) Normal form

Answer: A) Minterm

70.   The Karnaugh map cell corresponding to the minterm 𝑚5m5 in a 3-variable K-map is:

·         A) 𝐴‾𝐵𝐶ABC

·         B) 𝐴𝐵𝐶‾ABC

·         C) 𝐴𝐵‾𝐶ABC

·         D) 𝐴‾𝐵𝐶‾ABC

Answer: C) 𝐴𝐵‾𝐶ABC