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Computer Science for IGCSE & O level - Boolean Logic (Section 10)

1
Which logic gate produces a low output (0) only when all inputs are high (1)?
Answer
(D)
NAND gate
2
Which logic gate is represented by the Boolean expression (A · B)'?
Answer
(C)
NAND
3
What is the output of a 2-input AND gate when both inputs are HIGH (1)?
Answer
(B)
1
4
What type of gate is needed to build a half-adder circuit?
Answer
(B)
AND and XOR gates
5
Which of the following statements describes the behavior of an XOR gate?
Answer
(C)
Outputs HIGH if the inputs are different.
6
What is the primary function of the truth table?
Answer
(B)
To depict the output for all input combinations.
7
Which of the following statements correctly describes a NOR gate?
Answer
(C)
Outputs HIGH only if all inputs are LOW.
8
What is represented in the last section of the image?
Answer
(A)
Key terms
9
What is the output of an XOR gate if both inputs are LOW?
Answer
(A)
0
10
In Boolean algebra, which symbol represents the OR operation?
Answer
(A)
+
11
Which of the following is the correct symbol for a NOR gate?
Answer
(A)
A gate shaped like a D with a curved side and a bubble on the output
12
What is the primary role of a truth table in digital logic?
Answer
(C)
To describe the functionality of a logic gate or circuit.
13
What is the simplified form of the logic expression: A AND (A OR B)?
Answer
(A)
A
14
If the inputs to an OR gate are A=1 and B=0, what will be the output?
Answer
(B)
1
15
Which of the following is a fundamental building block in digital circuits?
Answer
(A)
Transistors
16
If A and B are inputs to an OR gate and A=1, B=0, and the output is X, what is the value of X?
Answer
(B)
1
17
In a full adder, how many inputs are required?
Answer
(C)
3
18
What is the output of a 2-input AND gate if the inputs are A=0 and B=0?
Answer
(A)
0
19
Which is the correct Boolean expression for a NAND gate with inputs A and B?
Answer
(B)
(A . B)'
20
What is the simplified Boolean expression for A OR (A AND B)?
Answer
(A)
A
21
If the inputs to an OR gate are A=0 and B=1, what is the output?
Answer
(B)
1
22
Which logic gate inverts its input?
Answer
(C)
NOT
23
Which of the following gates can be used to implement the expression A'B + AB'?
Answer
(B)
XOR gate
24
If a logic expression is (A AND B) OR (C AND D), which gate would be involved in the final stage?
Answer
(B)
OR gate
25
What is the output of a 2-input OR gate when both inputs are HIGH (1)?
Answer
(B)
1
26
What is the purpose of De Morgan's Law in digital logic?
Answer
(A)
To simplify complex Boolean expressions
27
What is the simplified Boolean expression for the expression: A AND (A OR B)?
Answer
(A)
A
28
What is the output of a 2-input NOR gate if the inputs are A=0 and B=1?
Answer
(A)
0
29
Which of the following gate is represented by a half-circle, with a straight edge on the input side?
Answer
(C)
NOT
30
What is the logical operation performed by a NOT gate?
Answer
(C)
Inversion
31
If the inputs to an XOR gate are A=1 and B=1, what is the output?
Answer
(A)
0
32
Which of these is a universal gate?
Answer
(C)
NAND
33
A NOR gate's output is the inverse of what other gate?
Answer
(B)
OR gate
34
What are the two possible output values of a basic logic gate?
Answer
C
D
35
What is the output of a 2-input NAND gate if both inputs are 1?
Answer
(A)
0
36
Which gate is implemented as a negation of an AND gate?
Answer
(D)
NAND
37
If the inputs to an OR gate are A=1 and B=0, what is the output?
Answer
(B)
1
38
Which of the following is the logical equivalent of the expression (A AND B)?
Answer
(C)
NOT (NOT A AND NOT B)
39
A gate that outputs a '1' only when all inputs are '1' is an:
Answer
(A)
AND gate
40
The XOR gate produces a HIGH output if:
Answer
(C)
The inputs are different
41
What is the output of a 3-input AND gate when the inputs are A=1, B=0, and C=1?
Answer
(A)
0
42
What is the primary purpose of using logic gates in digital circuits?
Answer
(B)
To perform mathematical operations
43
What is a key advantage of using logic gates to perform calculations in a computer?
Answer
(B)
They operate at very high speeds.
44
Which gate's output is LOW only if all inputs are HIGH?
Answer
(A)
NAND
45
In the half adder circuit, what is the sum and carry when A=1 and B=1?
Answer
(B)
Sum = 0, Carry = 1
46
In a digital circuit, the '0' state is typically represented by:
Answer
(B)
A low voltage
47
What is the output of an OR gate if all its inputs are HIGH (1)?
Answer
(B)
1
48
In a given truth table, the input columns are labeled A, B, and C. What is the maximum number of rows required in this truth table?
Answer
(B)
8
49
A logic gate has two inputs, A and B. If the output is 0 when A=0 and B=1, what type of gate is it?
Answer
(C)
NOR
50
Which logic gate produces a '1' output when both inputs are '0'?
Answer
(C)
NOR