600+ Digital Electronics and Logic Design Solved MCQs

1.

The 2s compliment form (Use 6 bit word) of the number 1010 is

A. 111100
B. 110110
C. 110111
D. 1011
Answer» B. 110110
2.

AB+(A+B)’ is equivalent to

A. a ex-nor b
B. a ex or b
C. (a+b)a
D. (a+b)b
Answer» A. a ex-nor b
3.

The hexadecimal number equivalent to (1762.46)8 is

A. 3f2.89
B. 3f2.98
C. 2f3.89
D. 2f3.98
Answer» B. 3f2.98
4.

A three input NOR gate gives logic high output only when

A. one input is high
B. one input is low
C. two input are low
D. all input are low
Answer» D. all input are low
5.

The absorption law in Boolean algebra say that

A. x + x = x
B. x . y = x
C. x + x . y = x
D. none of the above
Answer» C. x + x . y = x
6.

Logic X-OR operation of (4ACO)H & (B53F)H results

A. aacb
B. 0
C. abcd
D. ffff
Answer» D. ffff
7.

What is decimal equivalent of (11011.1000)2 ?

A. 22
B. 22.2
C. 20.2
D. 27.5
Answer» D. 27.5
8.

The negative numbers in the binary system can be represented by

A. sign magnitude
B. 2\s complement
C. 1\s complement
D. all of the above
Answer» A. sign magnitude
9.

Negative numbers cannot be represented in

A. signed magnitude form
B. 1’s complement form
C. 2’s complement form
D. none of the above
Answer» D. none of the above
10.

The answer of the operation (10111)2*(1110)2 in hex equivalence is

A. 150
B. 241
C. 142
D. 1.01e+08
Answer» C. 142
11.

The Hexadecimal number equivalent of (4057.06)8 is

A. 82f.027
B. 82f.014
C. 82f.937
D. 83f.014
Answer» B. 82f.014
12.

The NAND gate output will be low if the two inputs are

A. 0
B. 1
C. 10
D. 11
Answer» D. 11
13.

A binary digit is called a

A. bit
B. character
C. number
D. byte
Answer» A. bit
14.

What is the binary equivalent of the decimal number 368

A. 101110000
B. 110110000
C. 111010000
D. 1.11e+08
Answer» A. 101110000
15.

What is the binary equivalent of the Octal number 367

A. 11110111
B. 11100111
C. 110001101
D. 10111011 1
Answer» A. 11110111
16.

What is the binary equivalent of the Hexadecimal number 368

A. 1111101000
B. 1101101000
C. 1101111000
D. 1.11e+09
Answer» B. 1101101000
17.

What is the binary equivalent of the decimal number 1011

A. 1111110111
B. 1111000111
C. 1111110011
D. 1.11e+09
Answer» C. 1111110011
18.

The gray code equivalent of (1011)2 is

A. 1101
B. 1010
C. 1111
D. 1110
Answer» D. 1110
19.

The decimal equivalent of hex number 1A53 is

A. 6793
B. 6739
C. 6973
D. 6379
Answer» B. 6739
20.

( 734)8 =( )16

A. c 1 d
B. d c 1
C. 1 c d
D. 1 d c
Answer» D. 1 d c
21.

The simplification of the Boolean expression (A'BC')'+ (AB'C)' is

A. 0
B. 1
C. a
D. bc
Answer» B. 1
22.

The hexadecimal number ‘A0’ has the decimal value equivalent to

A. 80
B. 256
C. 100
D. 160
Answer» D. 160
23.

The Boolean expression A.B+ A.B+ A.B is equivalent to

A. a + b
B. a\.b
C. (a + b)\
D. a.b
Answer» A. a + b
24.

The 2’s complement of the number 1101101 is

A. 101110
B. 111110
C. 110010
D. 10011
Answer» D. 10011
25.

When simplified with Boolean Algebra (x + y)(x + z) simplifies to

A. x
B. x + x(y + z)
C. x(1 + yz)
D. x + yz
Answer» D. x + yz
26.

The code where all successive numbers differ from their preceding number by single bit is

A. binary code.
B. bcd.
C. excess – 3.
D. gray.
Answer» D. gray.
27.

-8 is equal to signed binary number

A. 10001000
B. oooo1000
C. 10000000
D. 11000000
Answer» A. 10001000
28.

DeMorgan’s first theorem shows the equivalence of

A. or gate and exclusive or gate.
B. nor gate and bubbled and gate.
C. nor gate and nand gate.
D. nand gate and not gate
Answer» B. nor gate and bubbled and gate.
29.

When signed numbers are used in binary arithmetic, then which one of the following notations would have unique representation for zero.

A. sign- magnitude.
B. 1’s complement.
C. 2’s complement.
D. 9’s compleme nt.
Answer» A. sign- magnitude.
30.

The decimal equivalent of Binary number 11010 is

A. 26
B. 36
C. 16
D. 23
Answer» A. 26
31.

1’s complement representation of decimal number of -17 by using 8 bit

A. 1110 1110
B. 1101 1101
C. 1100 1100
D. 0001 0001
Answer» A. 1110 1110
32.

The excess 3 code of decimal number 26 is

A. 0100 1001
B. 1011001
C. 1000 1001
D. 1001101
Answer» B. 1011001
33.

How many AND gates are required to realize Y = CD+EF+G

A. 4
B. 5
C. 3
D. 2
Answer» D. 2
34.

The hexadecimal number for (95.5)10 is

A. (5f.8) 16
B. (9a.b) 16
C. ( 2e.f) 16
D. ( 5a.4) 16
Answer» A. (5f.8) 16
35.

The octal equivalent of (247) 10 is

A. ( 252) 8
B. (350) 8
C. ( 367) 8
D. ( 400) 8
Answer» C. ( 367) 8
36.

The number 140 in octal is equivalent to

A. (96)10 .
B. ( 86) 10
C. (90) 10 .
D. none of these.
Answer» A. (96)10 .
37.

The NOR gate output will be low if the two inputs are

A. 11
B. 1
C. 10
D. all
Answer» D. all
38.

Convert decimal 153 to octal. Equivalent in octal will be

A. (231)8
B. ( 331) 8
C. ( 431) 8 .
D. none of these.
Answer» A. (231)8
39.

The decimal equivalent of ( 1100)2 is

A. 12
B. 16
C. 18
D. 20
Answer» A. 12
40.

The binary equivalent of (FA)16 is

A. 1010 1111
B. 1111 1010
C. 10110011
D. none of these
Answer» B. 1111 1010
41.

How many two-input AND and OR gates are required to realize Y=CD+EF+G

A. 22
B. 23
C. 33
D. none of these
Answer» A. 22
42.

The excess-3 code of decimal 7 is represented by

A. 1100
B. 1001
C. 1011
D. 1010
Answer» D. 1010
43.

When an input signal A=11001 is applied to a NOT gate serially, its output signal is

A. 111
B. 110
C. 10101
D. 11001
Answer» B. 110
44.

The result of adding hexadecimal number A6 to 3A is

A. dd
B. e0
C. f0
D. ef
Answer» B. e0
45.

A universal logic gate is one, which can be used to generate any logic function. Which of the following is a universal logic gate?

A. or
B. and
C. xor
D. nand
Answer» D. nand
46.

Karnaugh map is used for the purpose of

A. reducing the electronic circuits used.
B. to map the given boolean logic function.
C. to minimize the terms in a boolean expression.
D. to maximize the terms of a given a boolean expression .
Answer» C. to minimize the terms in a boolean expression.
47.

The 2’s complement of the number 1101110 is

A. 10001
B. 10001
C. 10010
D. none
Answer» C. 10010
48.

The decimal equivalent of Binary number 10101 is

A. 21
B. 31
C. 26
D. 28
Answer» A. 21
49.

How many two input AND gates and two input OR gates are required to realize Y = BD+CE+AB

A. 11
B. 42
C. 32
D. 23
Answer» C. 32
50.

Which of following are known as universal gates

A. nand & nor
B. and & or.
C. xor & or.
D. none.
Answer» A. nand & nor
51.

Convert the octal number 7401 to Binary.

A. 1.111e+11
B. 1.1111e+11
C. 1.111e+11
D. 1.11e+11
Answer» A. 1.111e+11
52.

Find the hex sum of (93)16 + (DE)16 .

A. (171)16
B. (271)16
C. (179)16
D. (181)16
Answer» A. (171)16
53.

Perform 2’s complement subtraction of (7)10 − (11)10 .

A. 1100 (or -4)
B. 1101 (or -5)
C. 1011 (or -3)
D. 1110 (or -6)
Answer» A. 1100 (or -4)
54.

What is the Gray equivalent of (25)10

A. 1101
B. 110101
C. 10110
D. 10101
Answer» D. 10101
55.

Simplify the Boolean expression F = C(B + C)(A + B + C).

A. c
B. bc
C. abc
D. a+bc
Answer» A. c
56.

Simplify the following expression into sum of products using Karnaugh map F(A,B,C,D) = (1,3,4,5,6,7,9,12,13)

A. a\b+c\ d+ a\d+bc\
B. a\b\+c\ d\+ a\d\+b\c\
C. a\b\+c\ d+ a\d+bc\
D. a\b+c\ d\+ a\d\+bc\
Answer» A. a\b+c\ d+ a\d+bc\
57.

Simplify F = (ABC)'+( AB)'C+ A'BC'+ A(BC)'+ AB'C.

A. ( a\ + b\ +c\ )
B. ( a\ + b +c )
C. ( a + b +c )
D. ( a + b\ +c\ )
Answer» A. ( a\ + b\ +c\ )
58.

Determine the binary numbers represented by 25.5

A. 11001.1
B. 11011.101
C. 10101.11
D. 11001.010 1
Answer» A. 11001.1
59.

Conversion of decimal number 10.625 into binary number:

A. 1010.101
B. 1110.101
C. 1001.11
D. 1001.101
Answer» A. 1010.101
60.

Conversion of fractional number 0.6875 into its equivalent binary number:

A. 0.1011
B. 0.1111
C. 0.10111
D. 0.0101
Answer» A. 0.1011
61.

Perform the following subtractions using 2’s complement method. 01000 – 01001

A. 1
B. 10
C. 11
D. 11110
Answer» A. 1
62.

Subtraction of 01100-00011 using 2’s complement method. :

A. 1001
B. 1000
C. 1010
D. 110
Answer» A. 1001
63.

Minimize the logic functionY(A,B,C,D) = IZm(0,1,2,3,5,7,8,9,11,14) . Using Karnaugh map.

A. abc d\ + a\ b\ + b\ c\ + b\ d+ a\d
B. abc d + a b + b\ c\ + b\ d+ a\d
C. a\ b\ + b\ c\ + b\ d+ a\d
D. abc d\ + a\ b\ + b\ c\ + b\ d
Answer» A. abc d\ + a\ b\ + b\ c\ + b\ d+ a\d
64.

Simplify the given expression to its Sum of Products (SOP) form Y = (A + B)(A + (AB)')C + A'(B+C')+ A'B+ ABC

A. ac+ bc+ a\b + a\ c\
B. ac+ bc+ a\b
C. bc+ a\b + a\ c\
D. ac+ a\b + a\ c\
Answer» A. ac+ bc+ a\b + a\ c\
65.

Convert the decimal number 82.67 to its binary, hexadecimal and octal equivalents

A. (1010010.1010 1011)2; (52.ab)16 ;
B. (1010010.10 101011)2; (52.ab)16 ;
C. (1010010.10 101011)2; (52.ab)16 ;
D. (1010010.
Answer» A. (1010010.1010 1011)2; (52.ab)16 ;
66.

Add 20 and (-15) using 2’s complement.

A. (100100 )2 or (+4)10
B. (000100 )2 or (-4)10
C. both (a) and (b)
D. none of the above
Answer» A. (100100 )2 or (+4)10
67.

Add 648 and 487 in BCD code.

A. 1135
B. 1136
C. 1235
D. 1138
Answer» A. 1135
68.

(23.6)10 = (X)2 FIND X

A. (10111.100110 0)2
B. (10101.1001 100)2
C. (10001.1001 100)2
D. (10111.10 00011)2
Answer» A. (10111.100110 0)2
69.

(65.535)10 =(X)16 FIND X

A. (41.88f5c28)16 .
B. (42.88f5c28 )16.
C. (41.88f5c)16.
D. (42.88f5c )16.
Answer» A. (41.88f5c28)16 .
70.

Convert the decimal number 430 to Excess-3 code:

A. 110110001
B. 110110000
C. 110110011
D. 11010000 1
Answer» A. 110110001
71.

Minimize the following logic function using K-maps F(A,B,C,D) = m(1,3,5,8,9,11,15) + d(2,13)

A. a b\ c\ + c\ d + b\d + ad
B. c\ d + b\d + ad
C. a b\ c\ + b\d + ad
D. a b\ c\ + c\ d + b\d
Answer» A. a b\ c\ + c\ d + b\d + ad
72.

Convert (2222)10 in Hexadecimal number.

A. 8ae
B. 8be
C. 93c
D. fff
Answer» A. 8ae
73.

Divide ( 101110) 2 by ( 101)2.

A. quotient -1001 remainder - 001
B. quotient - 1000 remainder - 001
C. quotient - 1001 remainder - 011
D. quotient - 1001 remainder -000
Answer» A. quotient -1001 remainder - 001
74.

Minimise the logic function (POS Form) F A,B,C,D) = PI M (1, 2, 3, 8, 9, 10, 11,14)× d (7, 15)

A. f=[(b+d’)+(b+ c’)’(a’+c’)+(a’ +b)]’
B. f=[(b+d’)+(b +c’)’(‘a’+c’)+ (a’+b)]’
C. f=[(b+d’)+(b +c’)’(‘a’+c’)+ (a’+b)]’
D. f=[(b+d’)+ (b+c’)’(‘a’ +c’)+(a’+b )]’
Answer» A. f=[(b+d’)+(b+ c’)’(a’+c’)+(a’ +b)]’
75.

Perform following subtraction (i) 11001-10110 using 1’s complement

A. 11
B. 111
C. 10
D. 10011
Answer» A. 11
76.

Perform following subtraction(ii) 11011-11001 using 2’s complement

A. 10
B. 111
C. 11
D. 10011
Answer» A. 10
77.

Reduce the following equation using k-map Y = (ABC)'+ A(CD)'+ AB'+ ABCD'+ (AB)'C

A. b\+(ad)\
B. b\
C. (ad)\
D. b\+ad
Answer» A. b\+(ad)\
78.

Write the expression for Boolean function F (A, B, C) = m (1,4,5,6,7) in standard POS form.

A. = (a+b+c)(a+b\ +c)(a+b\ +c\ )
B. = (a+b\ +c)(a+b\ +c\ )
C. = (a+b+c)(a+b \ +c)
D. = (a+b+c)(a +b\ +c\ )
Answer» A. = (a+b+c)(a+b\ +c)(a+b\ +c\ )
79.

Convert the decimal number 45678 to its hexadecimal equivalent number.

A. (b26e)16
B. (a26e)16
C. (b26b)16
D. (b32e)16
Answer» A. (b26e)16
80.

Convert (177.25)10 to octal.

A. (261.2)8
B. (260.2)8
C. (361.2)8
D. (251.2)8
Answer» A. (261.2)8
81.

Reduce the following equation using k-map Y = B C' D'+ A' B C' D+ A B C' D+ A' B C D+ A B C D

A. bc’ + bd
B. bc’ + bd+a
C. bc’ + bd + ac
D. bc’ + bd + ad
Answer» A. bc’ + bd
82.

8-bit 1’s complement form of –77.25 is

A. 1001101.01
B. 10110010.10 11
C. 01001101.00 10
D. 10110010
Answer» B. 10110010.10 11
83.

In computers, subtraction is generally carried out by

A. 9’s complement
B. 10’s complement
C. 1’s complement
D. 2’s compleme nt
Answer» D. 2’s compleme nt
84.

The answer of the operation (10111)2*(1110)2 in hex equivalence is

A. 150
B. 241
C. 142
D. 10101111 0
Answer» C. 142
85.

The decimal number equivalent of (4057.06)8 is

A. 2095.75
B. 2095.075
C. 2095.937
D. 2095.094
Answer» D. 2095.094
86.

12-bit 2’s complement of –73.75 is

A. 01001001.110 0
B. 11001001.11 00
C. 10110110.01 00
D. 10110110. 1100
Answer» C. 10110110.01 00
87.

What is decimal equivalent of BCD 11011.1100 ?

A. 22
B. 22.2
C. 20.2
D. 21.2
Answer» B. 22.2
88.

What is the binary equivalent of the decimal number 368

A. 101110000
B. 110110000
C. 111010000
D. 11110000 0
Answer» A. 101110000
89.

(2FAOC)16 is equivalent to

A. (195 084)10
B. (001011111 010 0000 1100)2
C. both (a) and (b)
D. none of these
Answer» B. (001011111 010 0000 1100)2
90.

The octal equivalent of hexadecimal (A.B)16 is

A. 47.21
B. 12.74
C. 12.71
D. 17.21
Answer» B. 12.74
91.

Logic X-OR operation of (4ACO)H & (B53F)H results

A. aacb
B. 0
C. ffff
D. abcd
Answer» C. ffff
92.

The simplified form of the Boolean expression (X+Y+XY)(X+Z) is

A. x + y + zx + y
B. xy – yz
C. x + yz
D. xz + y
Answer» C. x + yz
93.

The output of a logic gate is 1 when all its inputs are at logic 0. the gate is either

A. nand or an xo
B. or or an xn
C. o an and or xor
D. a nor or an xnor
Answer» D. a nor or an xnor
94.

2's complement of any binary number can be calculated by

A. adding 1\s complement twice
B. adding 1 to 1\s complement
C. subtracting 1 from 1\s complement.
D. calculating 1\s compleme nt and inverting most significant bit
Answer» B. adding 1 to 1\s complement
95.

Sum-of-Weights method is used                   

A. to convert from one number system to other
B. to encode data
C. to decode data
D. to convert from serial to parralel data
Answer» A. to convert from one number system to other
96.

The complement of a variable is always

A. 1
B. 0
C. inverse
D. none
Answer» C. inverse
97.

The difference of 111 - 001 equals

A. 100
B. 111
C. 1
D. 110
Answer» D. 110
98.

The Unsigned Binary representation can only represent positive binary numbers

A. true
B. false
C. both (a) and (b)
D. none of above
Answer» A. true
99.

which of the following rules states that if one input of an AND gate is always 1, the output is equal to the other input?

A. a +1 =1
B. a +a =a
C. a.a = a
D. a.1= a
Answer» C. a.a = a
100.

Which of the number is not a representative of hexadecimal system

A. 1234
B. abcd
C. 1001
D. defh
Answer» D. defh
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