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600+ Digital Electronics and Logic Design Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) , Electronics and Telecommunication Engineering [ENTC] .

101.

Which one of the following is NOT a valid rule of Boolean algebra?

A. a = a\
B. aa = a
C. a + 1 = 1
D. a + 0 = a
Answer» A. a = a\
102.

In the binary number ' 10011 ' the weight of the most significant digit is

A. 2^4(2 raise to power 4)
B. 2^3 (2 raise to power 3)
C. 2^0 (2 raise to power 0)
D. 2^1 (2 raise to power 1)
Answer» A. 2^4(2 raise to power 4)
103.

The binary value ' 1010110 ' is equivalent to decimal                   

A. 86
B. 87
C. 88
D. 89
Answer» A. 86
104.

2's complement of hexadecimal number B70A is

A. b70b
B. b709
C. 48f6
D. 48f5
Answer» C. 48f6
105.

2's complement of 5 is

A. 1101
B. 1011
C. 1010
D. 1100
Answer» B. 1011
106.

The 4-bit 2's complement representation of ' -7 ' is                        

A. 111
B. 1111
C. 1001
D. 110
Answer» C. 1001
107.

If we multiply ' 723 ' and ' 34 ' by representing them in floating point notation i.e. By first, converting them in floating point representation and then multiplying them, the value of mantissa of result will be                

A. 24.582
B. 2.4582
C. 24582
D. 0.24582
Answer» A. 24.582
108.

The output of the expression F=A+B+C will be Logic when A=0, B=1, C=1. the symbol ' + ' here represents OR Gate.

A. undefined
B. one
C. zero
D. 10 (binary)
Answer» B. one
109.

A NAND gate's output is LOW if

A. all inputs are low
B. all inputs are high
C. any input is low
D. any input is high
Answer» C. any input is low
110.

NOR gate is formed by connecting                 

A. or gate and then not gate
B. not gate and then or gate
C. and gate and then or gate
D. or gate and then and gate
Answer» C. and gate and then or gate
111.

The AND Gate performs a logical function

A. addition
B. subtraction
C. multiplicatio
D. division
Answer» C. multiplicatio
112.

The Extended ASCII Code (American Standard Code for Information Interchange) is a code

A. 2-bit
B. 7-bit
C. 8-bit
D. 16-bit
Answer» C. 8-bit
113.

The OR gate performs Boolean .

A. multiplication
B. subtraction
C. division
D. addition
Answer» D. addition
114.

The output of an AND gate is one when              

A. all of the inputs are one
B. any of the input is one
C. any of the input is zero
D. all the inputs are zero
Answer» A. all of the inputs are one
115.

A NOR's gate output is HIGH if

A. all inputs are high
B. any input is high
C. any input is low
D. all inputs are low
Answer» D. all inputs are low
116.

A logic circuit with an output X = A(Bar)BC+AB(Bar) consists of .

A. two and gates, two or gates, two inverters
B. three and gates, two or gates, one inverter
C. two and gates, one or gate, two inverters
D. two and gates, one or gate
Answer» C. two and gates, one or gate, two inverters
117.

the boolean expression AB'CD'is

A. a sumterm
B. a product ter
C. a literal ter
D. m always 1
Answer» B. a product ter
118.

The boolean expression X = AB + CD represents

A. two ors anded together
B. a 4-input and gate
C. two ands ored together
D. an exclusive- or
Answer» C. two ands ored together
119.

The expression is an example of Commutative Law for Multiplication.

A. ab+c = a+bc
B. a(b+c) = b(a+c)
C. ab=ba
D. a+b=b+a
Answer» C. ab=ba
120.

The total amount of memory that is supported by any digital system depends upon            

A. the organization of memory
B. the structure of memory
C. the size of decoding unit
D. the size of the address bus of the microproc essor
Answer» D. the size of the address bus of the microproc essor
121.

Addition of two octal numbers “36” and “71” results in                

A. 213
B. 123
C. 127
D. 345
Answer» C. 127
122.

In which of the following base systems is 123 not a valid number?

A. base 10
B. base 16
C. base8
D. base 3
Answer» D. base 3
123.

Storage of 1 KB means the following number of bytes

A. 1000
B. 964
C. 1024
D. 1064
Answer» D. 1064
124.

What is the octal equivalent of the binary number: 10111101

A. 675
B. 275
C. 572
D. 573
Answer» B. 275
125.

The binary code of (21.125)10 is

A. 10101.001
B. 10100.001
C. 10101.01
D. 10100.111
Answer» A. 10101.001
126.

A NAND gate is called a universal logic element because

A. it is used by everybody
B. any logic function can be realized by nand gates alone
C. all the minization techniques are applicable for optimum nand gate realization
D. many digital computers use nand gates.
Answer» B. any logic function can be realized by nand gates alone
127.

Digital computers are more widely used as compared to analog computers, because they are

A. less expensive
B. always more accurate and faster
C. useful over wider ranges of problem types
D. easier to maintain.
Answer» C. useful over wider ranges of problem types
128.

Most of the digital computers do not have floating point hardware because

A. floating point hardware is costly
B. it is slower than software
C. it is not possible to perform floating point addition by hardware
D. of no specific reason.
Answer» A. floating point hardware is costly
129.

The number 1000 would appear just immediately after

A. ffff (hex)
B. 1111
C. 7777 (octal)
D. all of the
Answer» D. all of the
130.

(1(10101)2 is

A. (37)10
B. ( 69)10
C. (41 )10
D. — (5)10
Answer» A. (37)10
131.

The number of Boolean functions that can be generated by n variables is equal to

A. 2n
B. 22 n
C. 2n-1
D. — 2n
Answer» B. 22 n
132.

Consider the representation of six-bit numbers by two’s complement, one’s
complement, or by sign and magnitude: In which representation is there overflow from
the addition of the integers 011000 and 011000?

A. two’s complement only
B. sign and magnitude and one’s complement only
C. two’s complement and one’s complement only
D. all three representa tions.
Answer» D. all three representa tions.
133.

Positive logic in a logic circuit is one in which

A. logic 0 and 1 are represented by 0 and positive voltage respectively
B. logic 0 and, - 1 are represented by negative and positive voltages respectively
C. logic 0 voltage level is higher than logic 1 voltage level
D. logic 0 voltage level is lower than logic 1 voltage level.
Answer» D. logic 0 voltage level is lower than logic 1 voltage level.
134.

Which of the following gate is a two-level logic gate

A. or gate
B. nand gate
C. exclusive or gate
D. not gate.
Answer» C. exclusive or gate
135.

An AND gate will function as OR if

A. all the inputs to the gates are “1”
B. all the inputs are ‘0’
C. either of the inputs is “1”
D. all the inputs and outputs are compleme nted.
Answer» D. all the inputs and outputs are compleme nted.
136.

An OR gate has 6 inputs. The number of input words in its truth table are

A. 6
B. 32
C. 64
D. 128
Answer» C. 64
137.

NAND. gates are preferred over others because these

A. have lower fabrication area
B. can be used to make any gate
C. consume least electronic power
D. provide maximum density in a chip.
Answer» B. can be used to make any gate
138.

In case of OR gate, no matter what the number of inputs, a

A. 1 at any input causes the
B. 1 at any input causes
C. 0 any input causes the
D. 0 at any input
Answer» A. 1 at any input causes the
139.

Excess-3 code is known as

A. weighted code
B. cyclic
C. self-
D. algebraic
Answer» C. self-
140.

Indicate which of the following three binary additions are correct? 1.1011 + 1010 = 10101
II. 1010 + 1101 = 10111
III. 1010 + 1101 = 11111

A. i and ii
B. ii and iii
C. iii only
D. ii and i
Answer» D. ii and i
141.

X – = Y + 1 means

A. x = x – y + 1
B. x = –x – y – 1
C. x = –x + y + 1
D. x= x – y – 1
Answer» A. x = x – y + 1
142.

A binary digit is called a

A. bit
B. byte
C. number
D. character
Answer» A. bit
143.

The ASCII code for letter A is

A. 1100011
B. 1111111
C. 1000001
D. 10011
Answer» C. 1000001
144.

Transistor is a

A. current controlled current device.
B. current controlled voltage device.
C. voltage controlled current device.
D. voltage controlled voltage device.
Answer» A. current controlled current device.
145.

A digital logic device used as a buffer should have what input/output characteristics?

A. high input impedance and high output impedance
B. low input impedance and high output impedance
C. low input impedance and low output impedance
D. high input impedance and low output impedance
Answer» D. high input impedance and low output impedance
146.

What is the standard TTL noise margin?

A. 5.0 v
B. 0.2 v
C. 0.8 v
D. 0.4 v
Answer» D. 0.4 v
147.

The range of a valid LOW input is:

A. 0.0 v to 0.4 v
B. 0.4 v to 0.8 v
C. 0.0 v to 1.8 v
D. 0.0 v to 2.8 v
Answer» B. 0.4 v to 0.8 v
148.

When an IC has two rows of parallel connecting pins, the device is referred to as:

A. a qfp
B. a dip
C. a phase splitter
D. cmos
Answer» B. a dip
149.

Which digital IC package type makes the most efficient use of printed circuit board space?

A. smt
B. to can
C. flat pack
D. dip
Answer» A. smt
150.

The digital logic family which has minimum power dissipation is

A. ttl
B. rtl
C. dtl
D. cmos
Answer» D. cmos

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