Digital Electronics Unit 2 – Combinational Logic: important questions for AKTU
Unit 2 (Combinational Logic) questions that AKTU repeats most often. This unit carries about 31 marks per paper. Start with the repeated questions, then the most asked topics.
Most repeated Unit 2 questions
- (i) Implement a full subtractor circuit using only NAND gates. (ii) Using 4:1 multiplexers, implement the following function F(A, B, C) = ∑m(0,2,3,5,7) (10 marks, 2022, Multiplexer and Demultiplexer) – also asked in 2022, 2023, 2025, 2026
- Design a full adder and full subtractor using NAND gates only. (10 marks, 2022, Adders and Subtractors) – also asked in 2022, 2023, 2025, 2026
- Implement the following function. F (A, B, C, D) = ∑m (0, 1, 3, 4, 7, 8, 9, 11, 14, 15) using 1. 8:1 MUX 2. 4:1 MUX (7 marks, 2025, Multiplexer and Demultiplexer) – also asked in 2022, 2023, 2024
Most important Unit 2 topic
- Adders and Subtractors (Unit 2: Combinational Logic) – asked 22 times in 2022, 2023, 2025, 2026
Most asked Unit 2 topics
- Adders and Subtractors – asked 22 times
- Multiplexer and Demultiplexer – asked 15 times
- Magnitude Comparator – asked 7 times
More Unit 2 previous year questions
- State the function of an encoder. (2 marks, 2026, Encoders and Decoders)
- What is a multiplexer? Write any two applications. (2 marks, 2026, Multiplexer and Demultiplexer)
- Design a full subtractor circuit using two half subtractors and basic gates. (7 marks, 2026, Adders and Subtractors)
- Explain the operation of a 4-bit priority encoder with truth table and logic diagram. (7 marks, 2026, Encoders and Decoders)
- Design a Full Adder using two Half Adders and basic gates. (7 marks, 2026, Adders and Subtractors)
Unit 2 syllabus topics
- Adders and Subtractors
- Multiplexer and Demultiplexer
- Encoders and Decoders
- Magnitude Comparator
- Multiplexed Display