1. SSC JE 24-Jan-2018 Shift-1
Q: Which of the following is a universal gate?
A. OR
B. AND
C. NAND
D. NOT
✅ Answer: C
Explanation: NAND and NOR gates are universal gates because all logic functions (AND, OR, NOT) can be built using them.
2. SSC JE 25-Jan-2018 Shift-2
Q: The output of an OR gate is 1 when:
A. All inputs are 1
B. All inputs are 0
C. At least one input is 1
D. At least one input is 0
✅ Answer: C
Explanation: The OR gate gives output 1 if any one or more inputs are 1.
3. SSC JE 27-Jan-2018 Shift-1
Q: What is the output of a 2-input XOR gate when both inputs are the same?
A. 1
B. 0
C. Input A
D. Input B
✅ Answer: B
Explanation: XOR gate gives output 1 only when inputs are different. If both are same (0,0 or 1,1), output is 0.
4. SSC JE 22-Jan-2018 Shift-2
Q: A NOT gate is also called as:
A. Inverter
B. Selector
C. Decoder
D. Encoder
✅ Answer: A
Explanation: A NOT gate is also known as an inverter, as it inverts the input logic level.
5. SSC JE 22-Jan-2018 Shift-1
Q: Which logic gate will have high output only when all inputs are high?
A. OR
B. XOR
C. AND
D. NAND
✅ Answer: C
Explanation: The AND gate gives output 1 only when all inputs are 1.
6. SSC JE 23-Jan-2018 Shift-1
Q: Which gate gives output 0 when all inputs are 1?
A. AND
B. NAND
C. OR
D. NOR
✅ Answer: B
Explanation: A NAND gate is the inverse of AND. If all inputs are 1, NAND gives output 0.
7. SSC JE 24-Jan-2018 Shift-2
Q: Which gate gives output 1 only when all inputs are 0?
A. AND
B. NOR
C. OR
D. NAND
✅ Answer: B
Explanation: NOR is the inverse of OR. OR gives 0 when all inputs are 0; hence, NOR gives 1 in that case.
8. SSC JE 27-Jan-2018 Shift-2
Q: Boolean expression for XOR gate is:
A. A + B
B. A.B
C. A'B + AB'
D. AB + AB'
✅ Answer: C
Explanation: The standard expression for XOR gate is A'B + AB', which represents output = 1 when inputs differ.
9. SSC JE 23-Jan-2018 Shift-2
Q: Logic gates are primarily made using:
A. Diodes only
B. Transistors only
C. Diodes and transistors
D. Resistors
✅ Answer: C
Explanation: Logic gates are constructed using a combination of diodes and transistors (Diode-Transistor Logic, Transistor-Transistor Logic).
10. SSC JE 24-Jan-2018 Shift-2
Q: Which gate has output 0 only when inputs are different?
A. XOR
B. XNOR
C. OR
D. AND
✅ Answer: B
Explanation: The XNOR gate is the inverse of XOR. It gives 1 when inputs are same, and 0 when they differ.