Logic Circuits and Design

Review all questions and their correct answers.

Question 1

A logic circuit that selects one of several input lines and forwards it to a single output line is called a:

Decoder
Encoder
Multiplexer
Demultiplexer

Question 2

A demultiplexer performs the __________ operation of a multiplexer.

Same
Reverse
Inverse
Combined

Question 3

Which of the following determines which input is selected in a MUX circuit?

Data lines
Control lines
Output line
Power supply

Question 4

How many select lines are required for a 16-to-1 multiplexer?

Question 5

The device that routes one input signal to many outputs is known as a:

Multiplexer
Encoder
Demultiplexer
Comparator

Question 6

A 3-to-8 decoder has how many outputs?

Question 7

The primary logic gate used in decoders is the:

OR
AND
XOR
NAND

Question 8

A 1-to-4 demultiplexer uses how many select lines?

Question 9

Which of the following devices can be used to implement any Boolean function?

Decoder
Multiplexer
Encoder
Demultiplexer

Question 10

The short form of Multiplexer is:

Question 11

In a demultiplexer, how many outputs are active at one time?

All
One
Two
None

Question 12

Which of the following is a real-world application of a demultiplexer?

Data compression
LED display control
Error detection
Voltage regulation

Question 13

A binary code where only one bit changes between successive values is called:

BCD
ASCII
Gray code
Excess-3

Question 14

The main purpose of using an encoder is to:

Increase data lines
Reduce data lines
Amplify signal
Store data

Question 15

Which logic gate has a HIGH output only when all inputs are LOW?

Question 16

The output of a NOT gate is always the __________ of its input.

Same
Inverse
Sum
Product

Question 17

How many possible input combinations exist for a 4-variable Boolean function?

Question 18

The truth table is used to:

Simplify circuits
Show all input-output relationships
Store data
Generate clock signals

Question 19

Which Boolean law states that A + A = A?

Commutative
Idempotent
Associative
Distributive

Question 20

According to De Morgan's Law, (A+B)' is equivalent to:

A' + B'
A'B'
A + B'
A' + B

Question 21

The main purpose of a decoder in memory systems is to:

Store data
Select memory locations
Refresh memory
Amplify data

Question 22

A 2-to-4 decoder requires how many input lines?

Question 23

The 4-bit binary number 1100 in BCD represents:

12
3
Invalid BCD code
C

Question 24

The binary number 1010 converted to Excess-3 is:

1101
1011
0111
1000

Question 25

The process of minimizing Boolean expressions is known as:

Expansion
Simplification
Compilation
Execution

Question 26

In a 4-variable K-map, how many cells are there?

Question 27

Which grouping is valid in a K-map?

Groups of 2, 4, 8 cells
Groups of 3, 5, 7 cells
Groups in a diagonal
Overlapping groups of different sizes

Question 28

The minimal form of the expression A + A'B is:

A + B
AB
B
A

Question 29

The binary number 1001101 equals decimal:

Question 30

Which circuit can perform addition of binary numbers?

Decoder
Full Adder
Multiplexer
Encoder

Question 31

A full adder adds __________ bits.

Question 32

A half adder does not include a __________ input.

Sum
Carry-out
Input A
Carry-in

Question 33

Which display device uses decoders for segment control?

LCD
7-segment display
LED Matrix
OLED

Question 34

In a 3-to-8 decoder, input 101 activates which output?

Question 35

How many select lines are required for a 32-to-1 multiplexer?

Question 36

The NOT operation in Boolean algebra corresponds to which gate?

Inverter
Buffer
AND gate
OR gate

Question 37

When both inputs of an OR gate are LOW, output is:

LOW
HIGH
Toggles
High Impedance

Question 38

Which law: A + AB = A?

Distributive
Absorption
Idempotent
Commutative

Question 39

A MUX can be used to implement:

Any logic function
Only adders
Only decoders
Only memory circuits

Question 40

What is the output of XOR when both inputs are the same?

1
0
Depends on the inputs
High Impedance

Question 41

What is the main function of combinational circuits?

Store data
Depend only on current input
Depend on past inputs
Generate a clock signal

Question 42

Which device stores data based on feedback?

Combinational circuit
Sequential circuit
Multiplexer
Decoder

Question 43

A flip-flop is used for:

Logic operations
Data storage
Signal amplification
Routing

Question 44

Which of the following is a sequential circuit?

Multiplexer
Counter
Full Adder
Decoder

Question 45

The binary equivalent of decimal 25 is:

11000
11001
10011
11010

Question 46

The decimal equivalent of 101111₂ is:

Question 47

The Boolean expression AB + A'C can represent a:

Decoder
Multiplexer
Encoder
Counter

Question 48

The simplification of A'B + AB' is:

A + B
A ⊕ B
A · B
A

Question 49

Which law states A(A + B) = A?

Distributive
Absorption
Associative
Idempotent

Question 50

Which is true for NAND gates?

It is a universal gate
It only adds numbers
It cannot be inverted
It requires 3 inputs

Question 51

A 2-input XOR gate is HIGH when:

Inputs are same
Inputs differ
Both inputs are HIGH
Both inputs are LOW

Question 52

The simplest form of A'B + AB' + AB is:

A + B
A ⊕ B
AB
A

Question 53

The complement of (AB + C)' is:

(A' + B')C'
A + B + C
A'B' + C'
(AB+C)'

Question 54

The Boolean expression for a NAND gate is:

(AB)'
A + B
AB
A'B'

Question 55

The logic function F = A + BC’ is:

Standard SOP
Standard POS
A canonical Form
Neither a standard SOP nor a standard POS

Question 56

Which code adds 0011 to each BCD representation of a decimal digit?

BCD
Gray Code
Excess-3
ASCII