Computer Science for IGCSE & O level - Boolean Logic (Section 11)
1
In the context of binary addition, what does the 'carry' bit represent?
Answer
(B)
The amount to be carried over to the next most significant bit column.
2
If you have an OR gate, and you want the output to be 0, what must the inputs be?
Answer
(C)
Both 0
3
Which gate is the inverse of an OR gate?
Answer
(B)
NOR
4
In a digital circuit, a NAND gate can be formed by combining an AND gate and a:
Answer
(A)
NOT gate
5
In the half adder circuit, the output is a carry if both inputs are:
Answer
(B)
1
6
Which of the following is true about logic gates?
Answer
(B)
They are made up of thousands of transistors
7
Which of these is not a common logic gate?
Answer
(D)
NOR
8
What logic gate produces an output of 1 only if its inputs are different?
Answer
(C)
XOR
9
Which of the following logic gates produces a 1 output if and only if all its inputs are 0?
Answer
(C)
NOR
10
When both inputs to a NAND gate are HIGH, the output is:
Answer
(B)
LOW
11
What is the simplified form of the expression A OR (A AND B)?
Answer
(A)
A
12
Which logic gate produces an output that is the inverse of the OR gate's output?
Answer
(B)
NOR gate
13
What is the fundamental function of a logic gate in digital circuits?
Answer
(B)
To perform logical operations.
14
The NAND gate is equivalent to an AND gate followed by what logic gate?
Answer
(C)
NOT gate
15
Which of the following statements describes an XOR gate?
Answer
(C)
Outputs HIGH if and only if inputs are different
16
A NOR gate can be made using which combination of gates?
Answer
(B)
OR and NOT
17
Which is the equivalent expression for NOT (A AND B)?
Answer
(B)
NOT A OR NOT B
18
What does the term 'binary value' represent?
Answer
(B)
A number in base 2
19
What is the carry output in a half adder if A=1 and B=0?
Answer
(A)
0
20
In a half adder circuit, what does 'sum' represent?
Answer
(A)
The result of adding two input bits without considering the carry.
21
The output of a NAND gate is LOW only when:
Answer
(C)
All inputs are HIGH
22
What is the output of a NAND gate if both inputs are 1?
Answer
(A)
0
23
What is the output of an XNOR gate when the inputs are 1 and 1?
Answer
(B)
1
24
What is the result of the Boolean expression A + A?
Answer
(C)
A
25
What does a Karnaugh map (K-map) help to simplify?
Answer
(A)
Logic circuits
26
Which logic gate is the complement of an OR gate?
Answer
(B)
NOR
27
A logic gate's function can be completely described by:
Answer
(B)
A truth table
28
In a series of logic operations represented by a truth table, what defines an input?
Answer
(A)
Independent variables that affect output.
29
If A = 1, what is the result of NOT A?
Answer
(A)
0
30
If the inputs to a 2-input AND gate are A=0 and B=0, what is the output?
Answer
(A)
0
31
Which of the following is equivalent to the logic expression NOT(A AND B)?
Answer
(C)
NOT A OR NOT B
32
What does the 'sum' output represent in a half adder?
Answer
(B)
The result of the binary addition
33
What type of gate results from inverting the output of a NAND gate?
Answer
(B)
OR
34
What is the output of a 2-input XOR gate if the inputs are A=1 and B=0?
Answer
(B)
1
35
How many logic gates are used to build a half adder circuit?
Answer
(C)
3
36
Which of the following is the simplified Boolean expression for a NAND gate with inputs A and B?
Answer
(C)
(A . B)'
37
What is the output of a 2-input AND gate when A=1 and B=0?
Answer
(A)
0
38
Which logic gate has an output of 1 only when both inputs are 1?
Answer
(B)
AND gate
39
If the inputs of an AND gate are A = 1 and B = 0, what will be the output?
Answer
(A)
0
40
Which type of gate can be described as an 'inverter'?
Answer
(C)
NOT gate
41
What type of logic gate is described by the expression NOT(A OR B)?
Answer
(C)
NOR gate
42
Which of the following Boolean expressions is equivalent to a NAND gate?
Answer
(D)
(A * B)'
43
Which gate outputs a HIGH (1) unless both inputs are HIGH (1)?
Answer
(A)
NAND
44
Which of the following gates is the most suitable for the application of a 'voting' system, where the output should be HIGH if a majority of inputs are HIGH?
Answer
(B)
OR
45
What is the purpose of a decoder in digital circuits?
Answer
(C)
To select one of several output lines based on the input.
46
Which one is a key advantage of using logic gates in computers?
Answer
(C)
They are very reliable.
47
What is the purpose of the NOT gate in digital circuits?
Answer
(B)
To invert the signal.
48
How many input combinations exist for a logic gate with two inputs?
Answer
(C)
4
49
A truth table is a table that shows the output of a logic gate for every possible combination of:
Answer
(B)
Inputs and outputs.
50
Which of these is the correct expression for the NOT gate?
