Q1. Digital electronics deals with:

A) Continuous signals
B) Discrete signals
C) Mechanical signals
D) Sound waves

Answer: B) Discrete signals

Explanation:
Digital electronics works with discrete values like 0 and 1 (binary form), unlike analog electronics which uses continuous signals.

Q2. The basic building block of digital electronics is:

A) Transistor
B) Logic Gate
C) Capacitor
D) Inductor

Answer: B) Logic Gate

Explanation:
Logic gates perform logical operations and are the foundation of digital circuits.

Q3. Which gate is called the universal gate?

A) AND
B) OR
C) NAND
D) XOR

Answer: C) NAND

Explanation:
NAND gate is called a universal gate because any logic circuit can be made using only NAND gates.

Q4. Which gate gives output 1 only when all inputs are 1?

A) OR
B) AND
C) NOT
D) NOR

Answer: B) AND

Explanation:
AND gate produces HIGH output only when all inputs are HIGH.

Q5. Which gate is also known as an inverter?

A) OR
B) NOT
C) XOR
D) NAND

Answer: B) NOT

Explanation:
NOT gate inverts the input. If input is 1, output becomes 0 and vice versa.

Q6. Binary number system uses:

A) 8 digits
B) 10 digits
C) 2 digits
D) 16 digits

Answer: C) 2 digits

Explanation:
Binary system uses only 0 and 1.

Q7. Octal number system uses base:

A) 2
B) 8
C) 10
D) 16

Answer: B) 8

Explanation:
Octal number system contains digits from 0 to 7.

Q8. Hexadecimal number system uses base:

A) 8
B) 10
C) 16
D) 2

Answer: C) 16

Explanation:
Hexadecimal uses digits 0–9 and letters A–F.

Q9. 1’s complement is obtained by:

A) Adding 1
B) Reversing bits
C) Subtracting 1
D) Multiplying by 2

Answer: B) Reversing bits

Explanation:
1’s complement means changing 0 to 1 and 1 to 0.

Q10. 2’s complement is obtained by:

A) Adding 1 to 1’s complement
B) Subtracting 1
C) Dividing by 2
D) Reversing digits

Answer: A) Adding 1 to 1’s complement

Explanation:
First take 1’s complement, then add 1 to get 2’s complement.

Q11. Boolean algebra was developed by:

A) Newton
B) George Boole
C) Einstein
D) Pascal

Answer: B) George Boole

Explanation:
Boolean algebra is named after George Boole.

Q12. In Boolean algebra, A + A =

A) 0
B) 1
C) A
D) A²

Answer: C) A

Explanation:
According to Idempotent Law, A + A = A.

Q13. In Boolean algebra, A . 1 =

A) 0
B) A
C) 1
D) A²

Answer: B) A

Explanation:
Anything AND with 1 remains unchanged.

Q14. In Boolean algebra, A + 0 =

A) 0
B) A
C) 1
D) A'

Answer: B) A

Explanation:
Anything OR with 0 remains unchanged.

Q15. XOR gate output is 1 when:

A) Inputs are same
B) Inputs are different
C) All inputs are 0
D) All inputs are 1

Answer: B) Inputs are different

Explanation:
Exclusive OR (XOR) gives HIGH output when inputs are different.

Q16. NOR gate is combination of:

A) AND + NOT
B) OR + NOT
C) XOR + NOT
D) NAND + NOT

Answer: B) OR + NOT

Explanation:
NOR = OR gate followed by NOT gate.

Q17. NAND gate is combination of:

A) AND + NOT
B) OR + NOT
C) XOR + NOT
D) NOR + NOT

Answer: A) AND + NOT

Explanation:
NAND = AND gate followed by NOT gate.

Q18. Gray code is used to:

A) Reduce errors
B) Increase speed
C) Increase memory
D) Reduce voltage

Answer: A) Reduce errors

Explanation:
Gray code changes only one bit at a time, reducing transition errors.

Q19. Error detecting code example is:

A) ASCII
B) Parity bit
C) BCD
D) Gray code

Answer: B) Parity bit

Explanation:
Parity bit helps detect errors during data transmission.

Q20. BCD stands for:

A) Binary Coded Decimal
B) Bit Coded Data
C) Binary Code Division
D) Basic Circuit Design

Answer: A) Binary Coded Decimal

Explanation:
BCD represents decimal digits using binary numbers.

Q21. TTL stands for:

A) Transistor Transistor Logic
B) Time Transfer Logic
C) Total Transistor Logic
D) Transfer Time Logic

Answer: A) Transistor Transistor Logic

Explanation:
TTL is a logic family using bipolar junction transistors.

Q22. CMOS stands for:

A) Complementary Metal Oxide Semiconductor
B) Common Metal Oxide System
C) Controlled MOS
D) Computer MOS

Answer: A) Complementary Metal Oxide Semiconductor

Explanation:
CMOS is widely used because of low power consumption.

Q23. CMOS consumes:

A) High power
B) Low power
C) Medium power
D) No power

Answer: B) Low power

Explanation:
CMOS technology is preferred for low power applications.

Q24. TTL is faster than:

A) CMOS
B) Relay
C) Vacuum tube
D) Analog circuit

Answer: A) CMOS

Explanation:
Traditional TTL generally has faster switching speed than basic CMOS.

Q25. Tri-state logic has:

A) 2 states
B) 3 states
C) 4 states
D) 5 states

Answer: B) 3 states

Explanation:
The three states are HIGH, LOW, and High Impedance (Z).

Q26. High impedance state means:

A) Output disconnected
B) Output 1
C) Output 0
D) Input blocked

Answer: A) Output disconnected

Explanation:
In Z-state, output behaves like it is disconnected from the circuit.

Q27. Digital IC stands for:

A) Integrated Circuit
B) Internal Circuit
C) Input Circuit
D) Intelligent Circuit

Answer: A) Integrated Circuit

Explanation:
IC means Integrated Circuit containing many components in one chip.

Q28. Which code is self-complementing?

A) Gray Code
B) Excess-3 Code
C) ASCII
D) BCD

Answer: B) Excess-3 Code

Explanation:
Excess-3 is self-complementing and useful in decimal arithmetic.

Q29. Signed binary numbers represent:

A) Only positive values
B) Only negative values
C) Positive and negative values
D) Decimal values only

Answer: C) Positive and negative values

Explanation:
Signed binary numbers include sign bit for positive/negative values.

Q30. The output of NOT(1) is:

A) 1
B) 0
C) Z
D) Undefined

Answer: B) 0

Explanation:
NOT gate inverts the input, so NOT(1) = 0.