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MCQOPTIONS
This section includes 223 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Considering X and Y as binary variables, the Boolean expression X + Y + 1 is equivalent to |
| A. | X |
| B. | 1 |
| C. | 0 |
| D. | Y |
| Answer» C. 0 | |
| 52. |
In the figure shown, the output Y is required to be Y = A.B + C̅.D̅. The gates G1 and G2 must be respectively. |
| A. | NOR, OR |
| B. | OR, NAND |
| C. | NAND, OR |
| D. | AND, NAND |
| Answer» B. OR, NAND | |
| 53. |
Assume x' represents negation of x the Boolean function x'y' + xy + x'y is equivalent to? |
| A. | x' + y |
| B. | x + y |
| C. | x + y' |
| D. | x' + y' |
| Answer» B. x + y | |
| 54. |
Consensus theorem is |
| A. | A’B + A’C + BC = A’B + A’C |
| B. | AB + A’C’ + BC = AB’ + A’C |
| C. | AB + A’C + BC = AB + A’C |
| D. | AB + A’C’ + BC = A’B’ + A’C |
| Answer» D. AB + A’C’ + BC = A’B’ + A’C | |
| 55. |
Considering X as a binary variable, the Boolean expression X.0 is equivalent to |
| A. | X |
| B. | 1 |
| C. | 0 |
| D. | X’ |
| Answer» D. X’ | |
| 56. |
A logic circuit shown below is used to implement the Boolean expression Y. Which of the following combinations of values of J and K will result in Y = AB |
| A. | J = 1, K = B̅ |
| B. | J = 1, K = B |
| C. | J = B, K = 1 |
| D. | J = B̅, K = 1 |
| Answer» B. J = 1, K = B | |
| 57. |
Boolean Algebra is used for designing and analysing: |
| A. | digital circuits |
| B. | secondary storage devices |
| C. | CD-ROMs |
| D. | none of the above |
| Answer» B. secondary storage devices | |
| 58. |
In Boolean algebra \(\left( {\overline {1 + 1} } \right).\left( {\overline {0 + 0} } \right) = ?\) |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | -1 |
| Answer» B. 1 | |
| 59. |
An expression \(f = \overline {\overline {AB} + \overline {A} + AB} \) can be reduced to |
| A. | A |
| B. | B |
| C. | 0 |
| D. | 1 |
| Answer» D. 1 | |
| 60. |
Identify the number of prime implicants and essential prime implicants for the functionf(A, B, C, D) = Σ m(0, 1, 4, 6, 7, 8, 10, 14, 15)(where m represents min terms) |
| A. | 7, 2 |
| B. | 6, 2 |
| C. | 7, 1 |
| D. | 6, 1 |
| Answer» B. 6, 2 | |
| 61. |
If A and B are two input in AND gates, the AND gate has an output of 1, when the values of A and B are |
| A. | A = 0, B = 0 |
| B. | A = 1, B = 1 |
| C. | A = 1, B = 0 |
| D. | A = 0, B = 1 |
| Answer» C. A = 1, B = 0 | |
| 62. |
All Digital circuit can be made using only ________ gates. |
| A. | AND |
| B. | NOT |
| C. | OR |
| D. | NOR |
| Answer» E. | |
| 63. |
_________ and _________ are called as universal gates. |
| A. | AND , OR |
| B. | NAND , NOR |
| C. | NOT , OR |
| D. | AND , NOT |
| Answer» C. NOT , OR | |
| 64. |
How many cells would be required in the Karnaugh map if 4 variables are involved preparing the map for function minimization? |
| A. | 4 |
| B. | 8 |
| C. | 12 |
| D. | 16 |
| Answer» E. | |
| 65. |
An XNOR gate produces an output only when the two inputs are: |
| A. | High |
| B. | Different |
| C. | Low |
| D. | Same |
| Answer» E. | |
| 66. |
A single transistor can be used to build which of the following digital logic gate? |
| A. | AND gate |
| B. | NOT gate |
| C. | OR gate |
| D. | NAND gate |
| Answer» C. OR gate | |
| 67. |
A + AB gets simplified to: |
| A. | AB |
| B. | B |
| C. | A + B |
| D. | A |
| Answer» E. | |
| 68. |
A logic probe is placed on the output of a digital circuit and the probe lamp is dimly lit. This display indicates ________ |
| A. | that an open or bad logic level exists |
| B. | a high level output |
| C. | a high frequency pulse train |
| D. | that the supply voltage is low |
| Answer» B. a high level output | |
| 69. |
A function of Boolean variables \({\rm{x}},{\rm{y\;and\;z}}\) is expressed in terms of the min-term as \({\rm{F}}\left( {{\rm{x}},{\rm{y}},{\rm{z}}} \right){\rm{\;}} = {\rm{\;\Sigma \;}}\left( {1,2,5,6,7} \right)\). Which one of the product of sums given below is equal to F(x,y,z) |
| A. | \(\left( {{\rm{\bar x}} + {\rm{\;\bar y}} + {\rm{\;\bar z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\left( {{\rm{x\;}} + {\rm{\;\bar y}} + {\rm{\;\bar z}}} \right)\) |
| B. | \(\left( {{\rm{x\;}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\left( {{\rm{x\;}} + {\rm{\;\bar y}} + {\rm{\;\bar z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\) |
| C. | \(\left( {{\rm{\bar x}} + {\rm{\;\bar y}} + {\rm{\;z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;\bar z}}} \right)\left( {{\rm{x\;}} + {\rm{\;\bar y}} + {\rm{\;z}}} \right)\left( {{\rm{x\;}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\) |
| D. | \(\left( {{\rm{x\;}} + {\rm{\;y\;}} + {\rm{\;\bar z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;\bar z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;\bar y}} + {\rm{\;z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;\bar y}} + {\rm{\;\bar z}}} \right)\) |
| Answer» C. \(\left( {{\rm{\bar x}} + {\rm{\;\bar y}} + {\rm{\;z}}} \right)\left( {{\rm{\bar x}} + {\rm{\;y\;}} + {\rm{\;\bar z}}} \right)\left( {{\rm{x\;}} + {\rm{\;\bar y}} + {\rm{\;z}}} \right)\left( {{\rm{x\;}} + {\rm{\;y\;}} + {\rm{\;z}}} \right)\) | |
| 70. |
Match the columns.Logic GatesSymbolDescription 1. a. OR Gate 2. b. XOR Gate 3. c. NOR Gate 4. d. AND Gate |
| A. | 1 - c, 2 - b, 3 - a, 4 - d |
| B. | 1 - b, 2 - a, 3 - c, 4 - d |
| C. | 1 - d, 2 - b, 3 - c, 4 - a |
| D. | 1 - a, 2 - b, 3 - c, 4 - d |
| Answer» E. | |
| 71. |
f(A, B, C, D) = (A + B + C̅ + D̅).(A̅ + C + D̅).(A̅ + B + C̅ + D̅).(B̅ + C).(B̅ + C̅).(A + B̅).(B̅ + D̅)The minimized function for the above expression is: |
| A. | f(A, B, C, D) = (A̅ + D̅) (C̅ + D̅) |
| B. | f(A, B, C, D) = B̅.(A̅ + D̅) (C̅ + D̅) |
| C. | f(A, B, C, D) = (B̅ A̅ + D̅) (C̅ + D̅) |
| D. | f(A, B, C, D) = (B̅.A̅.D̅) (C̅ + D̅) |
| Answer» C. f(A, B, C, D) = (B̅ A̅ + D̅) (C̅ + D̅) | |
| 72. |
A 3-variable truth table has a high output for the inputs : 010, 011 and 110. The Boolean expression for sum of product (SOP) can be written as: |
| A. | A̅B + BC̅ |
| B. | AB̅ + B̅C |
| C. | A̅ B̅ + BC |
| D. | AB̅ + B̅C̅ |
| Answer» B. AB̅ + B̅C | |
| 73. |
For a four variable K-Map, if each cell is assigned one integer value in range 0-15 then which is the cells adjacent to the cell corresponding to decimal value 7? |
| A. | 3, 5, 6 and 8 |
| B. | 3, 5, 10 and 11 |
| C. | 3, 5, 6 and 15 |
| D. | 4, 6, 8 and 15 |
| Answer» D. 4, 6, 8 and 15 | |
| 74. |
A̅ + B̅ = Q represents |
| A. | NOR gate |
| B. | NAND gate |
| C. | EX-OR gate |
| D. | AND gate |
| Answer» C. EX-OR gate | |
| 75. |
K-map is used to minimize the number of |
| A. | Flip-flops in digital circuits |
| B. | Layout spaces in digital circuits for fabrication |
| C. | Functions of 3, 4, 5 or 6 variables |
| D. | Registers in CPU |
| Answer» D. Registers in CPU | |
| 76. |
For the logic circuit shown in the figure, the output Y is given by |
| A. | (A B + C) DE |
| B. | (A + B) C + DE |
| C. | AB + C(D + E) |
| D. | (A + B) C + D + E |
| Answer» C. AB + C(D + E) | |
| 77. |
Considering X as a binary variable, the Boolean expression X.1 is equivalent to |
| A. | X |
| B. | 1 |
| C. | 0 |
| D. | X’ |
| Answer» B. 1 | |
| 78. |
Consider the following expression1. Y = f (A,B,C,D) = ∑(1,2,4,7,8,11,13,14)2.Y = f (A,B,C,D ) = ∑(3,5,7,10,11,12,13,14)3.Y = f(A,B,C,D) = π(0,3,5,6,9,10,12,15)4.Y = f(A,B,C,D) = π(0,1,2,4,6,8,9,15)which of these expression are equivalent of the expression Y = A⊕B⊕C⊕D |
| A. | 1 and 2 |
| B. | 1 and 4 |
| C. | 2 and 3 |
| D. | 1 and 3 |
| Answer» E. | |
| 79. |
A logic variable in either inverted or non-inverted from is called: |
| A. | minterm |
| B. | literal |
| C. | prime-implicant |
| D. | maxterm |
| Answer» C. prime-implicant | |
| 80. |
Consider the Boolean function, F(w,x,y,z) = wy +xy + w̅x̅y + xz + x̅y̅z̅. Which one of the following is the complete set of essential prime implicants? |
| A. | w, y, xz, x̅ z̅ |
| B. | w, y, xz |
| C. | y, x̅ y̅ z̅ |
| D. | y, xz, x̅ z̅ |
| Answer» E. | |
| 81. |
Product of Maxterms representation for the Boolean function F = B̅D + A̅D + BD is |
| A. | Π M (1, 3, 5, 7) |
| B. | Π M (0, 2, 4, 6) |
| C. | Π M (0,1 ,2, 3) |
| D. | Π M (4, 5, 6, 7) |
| Answer» C. Π M (0,1 ,2, 3) | |
| 82. |
Observe the given figure and calculate the Boolean expression. |
| A. | A'. (B + C) |
| B. | A. (B' + C') |
| C. | A. (B + C') |
| D. | A'. (B' + C') |
| Answer» D. A'. (B' + C') | |
| 83. |
Digital input signals A, B, C with A as the MSB and C as the LSB are used to realize the Boolean function F = m0 + m2 + m3 + m5 + m7, where mi denotes the ith minterm. In addition, F has a don’t care for m1. The simplified expression for F is given by: |
| A. | \(\bar A\bar C + \bar BC + AC\) |
| B. | \(\bar A + C\) |
| C. | \(\bar C + A\) |
| D. | \(\bar AC + BC + A\bar C\) |
| Answer» C. \(\bar C + A\) | |
| 84. |
A 2n variable Karnaugh Map has _______ cells. |
| A. | 4n2 |
| B. | 42n |
| C. | 22n |
| D. | n2n |
| Answer» D. n2n | |
| 85. |
A and B are the inputs of a 2 input gate. Y is its output. Identify the gate whose truth table is given. ABY001011101110 |
| A. | AND |
| B. | OR |
| C. | NOR |
| D. | None of the above |
| Answer» E. | |
| 86. |
If A = 1, B = 1, what will be the values of Y and Z? |
| A. | Y = 0, Z = 0 |
| B. | Y = 1, Z = 0 |
| C. | Y = 0, Z = 1 |
| D. | Y = 1, Z = 1 |
| Answer» D. Y = 1, Z = 1 | |
| 87. |
Given f(A, B, C, D) = ∑ m(0, 1, 2, 6, 8, 9, 10, 11) + ∑ d(3, 7, 14, 15) is a Boolean function, where m represents min-terms and d represents don’t cares. The minimal sum of products expression for f is |
| A. | f = AB̅ + CB |
| B. | f = B̅ + C |
| C. | f = D̅ + A |
| D. | f = A̅B + C̅D |
| Answer» C. f = D̅ + A | |
| 88. |
NAND and NOR gates are called ‘Universal’ gates primarily because |
| A. | They are available everywhere |
| B. | They are widely used in I.C. packages |
| C. | They can be combined to produce AND, OR and NOR gate |
| D. | They can be manufactured easily |
| Answer» D. They can be manufactured easily | |
| 89. |
Match the following list: List -1 List- 2(a)a ⊕ b = 0ia ≠ b(b)\(\overline {\left( {a + b} \right)}\) = 0iia = b(c)a̅ . b = 0iiia = 1 or b = 1(d)a ⊕ b = 1iva = 1 or b = 0 The correct code is: |
| A. | a - iii, b - ii, c - i, d - iv |
| B. | a - ii, b - iii, c - iv, d - i |
| C. | a - iii, b - ii, c - iv, d - i |
| D. | a - ii, a - iii, a - i, a - iv |
| Answer» C. a - iii, b - ii, c - iv, d - i | |
| 90. |
Considering X and Y as binary variables, the Boolean expression Y + XY is equivalent to |
| A. | X |
| B. | 1 |
| C. | 0 |
| D. | Y |
| Answer» E. | |
| 91. |
A NOR gate is called Universal Logic Gate because |
| A. | It can be used without need of any other gate type |
| B. | It can be used only with AND gate universally |
| C. | It can be used only with OR gate universally |
| D. | It can be used only with NOT gate universally |
| Answer» B. It can be used only with AND gate universally | |
| 92. |
A*B*A, where * represents XOR, is equal to: |
| A. | B |
| B. | ABA |
| C. | A̅ |
| D. | A |
| Answer» B. ABA | |
| 93. |
Logic function (A̅ + B) (A + B) can be reduced to” |
| A. | B |
| B. | B̅ |
| C. | A |
| D. | A̅ |
| Answer» B. B̅ | |
| 94. |
If A̅ + AB = 0, find the values of A and B. |
| A. | A = 1 and B = 1 |
| B. | A = 1 and B = 0 |
| C. | A = 0 and B = 1 |
| D. | A = 0 and B = 0 |
| Answer» C. A = 0 and B = 1 | |
| 95. |
Following is the K-map of a Boolean function of five variables P, Q, R, S, and X. The minimum sum-of-product (SOP) expression for the function is |
| A. | P̅Q̅SX̅ + PQ̅SX̅ + QR̅S̅X + QRS̅X |
| B. | Q̅SX̅ + QS̅X |
| C. | Q̅SX + QS̅X |
| D. | Q̅S + QS̅ |
| Answer» C. Q̅SX + QS̅X | |
| 96. |
AND Function in ladder logic uses: |
| A. | Normally closed contacts in parallel |
| B. | Normally closed contacts in series |
| C. | Normally open contacts in series |
| D. | Normally open contacts in parallel |
| Answer» D. Normally open contacts in parallel | |
| 97. |
NOR Gate is equal to |
| A. | OR Gate with negated inputs |
| B. | NAND gate with negated output |
| C. | NAND gate with negated input |
| D. | None of these |
| Answer» D. None of these | |
| 98. |
Dual of the Boolean expression A. (B + C) = A.B + A.C |
| A. | A + (B + C) = A.B + A.C |
| B. | A. (B + C) = (A + B). (A.C) |
| C. | A + B.C = (A + B).(A + C) |
| D. | None of the above |
| Answer» D. None of the above | |
| 99. |
Given f1 , f3 and f in canonical sum of products form (in decimal) for the circuitf1 Σm (4, 5, 6, 7, 8), f3 Σm (1, 6, 15) and f Σm (1, 6, 8, 15) then f2 is |
| A. | ∑(4,6) |
| B. | ∑(4,8) |
| C. | ∑(6,8) |
| D. | ∑(4,6,8) |
| Answer» D. ∑(4,6,8) | |
| 100. |
InputsOutputsXYZ000011101110Observe the given table. The truth table represents _______ gate. |
| A. | NAND |
| B. | XOR |
| C. | AND |
| D. | OR |
| Answer» C. AND | |