1What is the binary equivalent of the decimal number 10?
Number system (conversion)
Easy
A.1100
B.1010
C.0110
D.1001
Correct Answer: 1010
Explanation:
To convert decimal 10 to binary, we use division by 2: 10/2 gives a quotient of 5 and remainder 0. 5/2 gives a quotient of 2 and remainder 1. 2/2 gives a quotient of 1 and remainder 0. 1/2 gives a quotient of 0 and remainder 1. Reading the remainders from bottom to top gives 1010.
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2Which logic gate is known as an inverter?
logic gates
Easy
A.AND gate
B.XOR gate
C.OR gate
D.NOT gate
Correct Answer: NOT gate
Explanation:
The NOT gate is called an inverter because it inverts the input signal. A HIGH (1) input becomes a LOW (0) output, and a LOW (0) input becomes a HIGH (1) output.
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3According to Boolean algebra, what is the value of the expression ?
boolean algebra
Easy
A.
B.0
C.1
D.A
Correct Answer: 1
Explanation:
This is the complement law. If A is 0, is 1, so . If A is 1, is 0, so . In both cases, the result is 1.
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4What is the Binary Coded Decimal (BCD) representation of the decimal digit 7?
codes (B-G,G-B,Excess-3,BCD)
Easy
A.0111
B.1000
C.0110
D.111
Correct Answer: 0111
Explanation:
In BCD, each decimal digit is represented by its 4-bit binary equivalent. The binary equivalent of the decimal number 7 is 0111.
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5In a Karnaugh map (K-map), a group of two adjacent 1s is called a:
K- Map ( up to 4 variables)
Easy
A.Pair
B.Quad
C.Octet
D.Minterm
Correct Answer: Pair
Explanation:
A group of two adjacent cells containing '1' in a K-map is called a pair. It eliminates one variable from the resulting term.
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6The Boolean expression is in which standard form?
SOP and POS
Easy
A.Sum of Products (SOP)
B.Canonical SOP
C.Canonical POS
D.Product of Sums (POS)
Correct Answer: Sum of Products (SOP)
Explanation:
The expression is a sum of several product terms (AB and A'C). This format is known as the Sum of Products (SOP) form.
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7What is the decimal equivalent of the binary number 1101?
Number system (conversion)
Easy
A.13
B.15
C.12
D.11
Correct Answer: 13
Explanation:
To convert 1101 to decimal: .
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8Which of the following logic gates is considered a universal gate?
logic gates
Easy
A.NAND
B.OR
C.AND
D.XOR
Correct Answer: NAND
Explanation:
NAND and NOR gates are called universal gates because any other logic gate (like AND, OR, NOT) can be constructed using only NAND gates or only NOR gates.
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9According to De Morgan's first theorem, is equal to:
boolean algebra
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
De Morgan's first theorem states that the complement of a sum is equal to the product of the complements. Thus, .
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10What is the Excess-3 code for the decimal digit 5?
codes (B-G,G-B,Excess-3,BCD)
Easy
A.0101
B.1000
C.0111
D.1001
Correct Answer: 1000
Explanation:
The Excess-3 code is found by adding 3 to the decimal digit and then converting the result to its 4-bit binary form. For digit 5, . The 4-bit binary for 8 is 1000.
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11What is the primary purpose of using a Karnaugh map (K-map)?
K- Map ( up to 4 variables)
Easy
A.To convert number systems
B.To draw logic circuits
C.To perform binary arithmetic
D.To simplify Boolean expressions
Correct Answer: To simplify Boolean expressions
Explanation:
A K-map is a graphical method used to simplify Boolean algebra expressions without having to use Boolean algebra theorems and laws.
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12The output of an AND gate is HIGH (1) only when:
logic gates
Easy
A.Any input is HIGH
B.All inputs are LOW
C.The inputs are different
D.All inputs are HIGH
Correct Answer: All inputs are HIGH
Explanation:
The AND gate functions like a logical 'multiplication'. Its output is 1 only if all of its inputs are 1. If any input is 0, the output will be 0.
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13The hexadecimal number 'F' is equivalent to which decimal number?
Number system (conversion)
Easy
A.15
B.16
C.14
D.10
Correct Answer: 15
Explanation:
The hexadecimal system uses digits 0-9 and letters A-F. The letter F represents the highest value, which is 15 in the decimal system.
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14A product term that contains every variable of a function, either complemented or uncomplemented, is called a:
SOP and POS
Easy
A.SOP term
B.Literal
C.Minterm
D.Maxterm
Correct Answer: Minterm
Explanation:
A minterm is a product term (AND term) in a Boolean expression that includes all the variables of the function. It corresponds to a single '1' in the function's truth table.
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15What is the Gray code equivalent of the binary number 1011?
codes (B-G,G-B,Excess-3,BCD)
Easy
A.1011
B.1110
C.1101
D.0100
Correct Answer: 1110
Explanation:
To convert binary to Gray code: The first bit (MSB) remains the same. Then, XOR each binary bit with the bit to its left. So, for 1011: G3=1; G2=1 XOR 0=1; G1=0 XOR 1=1; G0=1 XOR 1=0. The result is 1110.
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16An XOR gate produces a HIGH (1) output when:
logic gates
Easy
A.The number of HIGH inputs is even
B.The number of HIGH inputs is odd
C.All inputs are LOW
D.All inputs are HIGH
Correct Answer: The number of HIGH inputs is odd
Explanation:
The eXclusive-OR (XOR) gate gives a HIGH output only when its inputs are different. For a 2-input gate, this means one input is 0 and the other is 1, which means there is an odd number of HIGH inputs (one).
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17The Boolean law which states that is known as the:
boolean algebra
Easy
A.Associative law
B.Identity law
C.Distributive law
D.Commutative law
Correct Answer: Commutative law
Explanation:
The Commutative law of addition states that the order of variables in an OR operation does not affect the result, so is the same as .
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18What is the binary equivalent of the hexadecimal number 2A?
Number system (conversion)
Easy
A.00101010
B.00101011
C.10101010
D.00111010
Correct Answer: 00101010
Explanation:
To convert from hexadecimal to binary, convert each hex digit to its 4-bit binary equivalent. '2' is 0010 and 'A' (which is 10 in decimal) is 1010. Combining them gives 00101010.
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19What is the binary equivalent of the Gray code 1101?
codes (B-G,G-B,Excess-3,BCD)
Easy
A.0110
B.1101
C.1001
D.1010
Correct Answer: 1001
Explanation:
To convert Gray to binary: The MSB remains the same. Then, XOR the current binary bit with the next Gray code bit. For 1101: B3=1; B2=B3 XOR G2 = 1 XOR 1=0; B1=B2 XOR G1 = 0 XOR 0=0; B0=B1 XOR G0 = 0 XOR 1=1. The result is 1001.
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20The truth table for which gate shows that the output is 1 only when all inputs are 0?
logic gates
Easy
A.OR gate
B.NOR gate
C.AND gate
D.NAND gate
Correct Answer: NOR gate
Explanation:
A NOR gate is an OR gate followed by a NOT gate. The OR gate output is 0 only when all inputs are 0. The inverter then changes this 0 to a 1. For all other input combinations, the OR output is 1, which the NOR inverts to 0.
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21What is the decimal equivalent of the hexadecimal number ?
Number system (conversion)
Medium
A.687.50
B.687.25
C.678.50
D.587.25
Correct Answer: 687.25
Explanation:
To convert to decimal, we use place values: \n \n \n.
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22The result of the binary subtraction using 2's complement arithmetic is:
Number system (conversion)
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The correct option follows directly from the given concept and definitions.
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23What is the Excess-3 code representation of the decimal number 58?
codes (B-G,G-B,Excess-3,BCD)
Medium
A.0111 1010
B.1000 1011
C.1001 1100
D.0101 1000
Correct Answer: 1000 1011
Explanation:
The correct option follows directly from the given concept and definitions.
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24Convert the Gray code 1101 to its binary equivalent.
codes (B-G,G-B,Excess-3,BCD)
Medium
A.1010
B.1011
C.1110
D.1001
Correct Answer: 1001
Explanation:
To convert Gray to binary: \n1. The Most Significant Bit (MSB) of the binary number is the same as the MSB of the Gray code. So, Binary MSB = 1. \n2. XOR the current binary bit with the next Gray code bit to get the next binary bit. \n \n \n \n. \nSo, the binary number is 1001.
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25Convert the binary number 10110 to its Gray code equivalent.
codes (B-G,G-B,Excess-3,BCD)
Medium
A.11101
B.10101
C.11110
D.11011
Correct Answer: 11101
Explanation:
To convert binary to Gray: \n1. The MSB of the Gray code is the same as the MSB of the binary number. So, Gray MSB = 1. \n2. XOR each binary bit with the next binary bit to its right. \n \n \n \n \n. \nSo, the Gray code is 11101.
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26What is the minimum number of 2-input NAND gates required to implement the Boolean function (XOR)?
logic gates
Medium
A.5
B.3
C.4
D.6
Correct Answer: 4
Explanation:
The XOR function is . This can be implemented using NAND gates as . This circuit configuration requires exactly 4 NAND gates. It's a standard and optimized implementation.
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27The output of a 3-input NOR gate is passed through an inverter. This combination is equivalent to a:
logic gates
Medium
A.3-input XOR gate
B.3-input NAND gate
C.3-input AND gate
D.3-input OR gate
Correct Answer: 3-input OR gate
Explanation:
A 3-input NOR gate produces the output . When this output is passed through an inverter (NOT gate), the result is , which simplifies to . This is the function of a 3-input OR gate.
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28Simplify the Boolean expression using Boolean algebra rules.
boolean algebra
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
This expression is an example of the Consensus Theorem: . Here, X=A, Y=B, Z=C. The term is redundant. So, the expression simplifies to . \nExpanding this: . \nApplying consensus again on this result: .
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29What is the complement of the function ?
boolean algebra
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
To find the complement of , we use De Morgan's theorem. \n \n \n \n.
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30Which of the following is the canonical Sum of Products (SOP) form for the function ?
SOP and POS
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
We expand each term to include all variables: \n1. . Then, . These are minterms . \n2. . These are minterms . \nCombining and removing duplicates, we get minterms 1, 4, 5, 6, 7. So, .
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31A 3-variable function is represented by the SOP expression . What is its equivalent canonical Product of Sums (POS) expression?
SOP and POS
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The POS form is derived from the maxterms, which correspond to the input combinations for which the function is 0. For a 3-variable function, the possible minterm indices are 0 to 7. The given minterms (where F=1) are 0, 2, 3, 5, 7. The missing indices are 1, 4, 6. These are the maxterm indices. Therefore, the canonical POS expression is .
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32Simplify the Boolean function using a Karnaugh map.
K- Map ( up to 4 variables)
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Placing the minterms on a 3-variable K-map reveals two groups: \n1. A quad (group of 4) can be formed with minterms . This group simplifies to . \n2. A pair (group of 2) can be formed with minterms . This group simplifies to . \nCombining these gives the simplified expression .
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33Using a K-map, simplify the function .
K- Map ( up to 4 variables)
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
When the minterms are plotted on a 4-variable K-map, two main groups can be identified: \n1. A group of four consisting of minterms . This group simplifies to the term . \n2. A group of four consisting of minterms . This group simplifies to the term . \nThe final simplified SOP expression is the sum of these terms: , which is the XNOR function of B and D.
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34Find the simplified Product of Sums (POS) expression for the function .
K- Map ( up to 4 variables)
Medium
A.$(A'+C)(B'+C)
B.
C.
D.
Correct Answer:
Explanation:
To find the POS expression, we group the zeros on the K-map. The minterms where F=1 are 0, 1, 2, 4, 5. Therefore, the zeros are at minterm locations 3, 6, 7. \nOn the K-map: \n1. Group the zeros at (011) and (111). This pair simplifies to the SOP term . The corresponding maxterm is . \n2. Group the zeros at (110) and (111). This pair simplifies to the SOP term . The corresponding maxterm is . Wait, this is not optimal. Let's regroup.\n1. Group zeros at and . This gives SOP term , so POS term is . \n2. Group zeros at and . Let's try and . The group is . Let's try and . Wait, zeros are at 3,6,7. and simplifies to . This gives POS term . The zero at is grouped with , which gives . This gives POS term . This gives . This is not an option. Let's re-examine the minterms. Zeroes are 3,6,7. K-map for zeroes: Minterm 3 (A'BC), 6 (ABC'), 7 (ABC). Grouping 3 and 7 gives BC. Grouping 6 and 7 gives AB. So F' = AB + BC. Then F = (F')' = (AB+BC)' = (A'+B')(B'+C'). This is a correct derivation.
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35An AND gate has its inputs tied to the outputs of two separate XNOR gates. The first XNOR has inputs A and B. The second XNOR has inputs C and D. What is the final Boolean expression for the circuit's output?
logic gates
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The output of the first XNOR gate is . The output of the second XNOR gate is . These two outputs are the inputs to the AND gate. Therefore, the final output expression is the logical AND of the two XNOR outputs, which is .
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36Applying the law of absorption, which of the following expressions is equivalent to ?
boolean algebra
Medium
A.X
B.Y
C.X + Y
D.XY
Correct Answer: X + Y
Explanation:
This is a reduction theorem, not the absorption law. It can be proven: \n (Distributive Law) \nSince , the expression becomes: \n. This rule, , is a fundamental identity used for simplification.
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37Convert the decimal number to its octal equivalent.
Number system (conversion)
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
We convert the integer and fractional parts separately. \nInteger Part (43): \n remainder $3$ \n remainder $5$ \nReading remainders from bottom up gives . \nFractional Part (0.375): \n \nReading the integer part of the product gives . \nCombining both parts, we get .
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38Which of the following 4-bit groups represents an invalid state in 8421 BCD (Binary-Coded Decimal)?
codes (B-G,G-B,Excess-3,BCD)
Medium
A.1001
B.1100
C.0110
D.0001
Correct Answer: 1100
Explanation:
BCD code uses 4 bits to represent decimal digits from 0 to 9. The bit patterns for 0 (0000) to 9 (1001) are valid. The bit pattern 1100 corresponds to decimal 12. Since this is greater than 9, it is an invalid representation for a single decimal digit in BCD.
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39The POS expression for a function is . What is the equivalent SOP expression?
SOP and POS
Medium
A.
B.AB + A'B$
C.,
D.
Correct Answer:
Explanation:
We can expand the POS expression using the distributive law: \n \n \nSince and , the expression simplifies to: \n. This is the SOP expression for the XOR function.
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40Simplify the function with don't care conditions .
K- Map ( up to 4 variables)
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The correct option follows directly from the given concept and definitions.