Engineering Chemistry Unit 4 – Water Technology and Fuels: important questions for AKTU
Unit 4 (Water Technology and Fuels) questions that AKTU repeats most often. This unit carries about 26 marks per paper. Start with the repeated questions, then the most asked topics.
Most repeated Unit 4 questions
- A sample of coal was burnt in a bomb calorimeter. The following data were obtained: Mass of coal = 0.92 g, Mass of water = 2500 g, Water equivalent of calorimeter = 600 g, Rise in temperature = 2.85°C, Percentage of hydrogen in coal = 3.2%. Calculate HCV and LCV of coal. (Latent heat of steam = 587 cal/g) (7 marks, 2026, Calorific Value of Fuels) – also asked in 2021, 2022, 2023, 2024, 2025
- Calculate the amount of lime (87% pure) and soda (91% pure) required to soften 1,00,000 litres of water containing: Ca(HCO₃)₂ = 32.4 mg/L, Mg(HCO₃)₂ = 29.2 mg/L, MgCl₂ = 19 mg/L, CaSO₄ = 13.6 mg/L, CO₂ = 22 mg/L. (7 marks, 2026, Water Softening Techniques) – also asked in 2021, 2022, 2023, 2024, 2025
- Explain the Lime–Soda process of water softening. What are the advantages and limitations of this process? Calculate the amount of lime and soda required for the treatment of 10,000 litres of water whose analysis is as follows (in mg/L): Mg(HCO3)2=73; CaSO4=102; MgCl2=95; MgSO4=24; Ca(HCO3)2=121.5; NaCl=55. (7 marks, 2025, Water Softening Techniques) – also asked in 2021, 2022, 2023, 2024, 2026
Most important Unit 4 topic
- Water Softening Techniques (Unit 4: Water Technology and Fuels) – asked 16 times in 2021, 2022, 2023, 2024, 2025, 2026
Most asked Unit 4 topics
- Water Softening Techniques – asked 16 times
- Calorific Value of Fuels – asked 15 times
- Coal Analysis – asked 6 times
More Unit 4 previous year questions
- What is Calgon conditioning? Write its chemical reaction. (2 marks, 2026, Water Softening Techniques)
- When does Gross Calorific Value (GCV) equal Net Calorific Value (NCV)? (2 marks, 2026, Calorific Value of Fuels)
- Compare Ion Exchange process and Zeolite process for water softening. Under what conditions is each process preferred? (7 marks, 2026, Water Softening Techniques)
- Why zeolite softener is not recommended for obtaining feed water for high pressure boilers? (2 marks, 2025, Water Softening Techniques)
- Which type of water contamination- chemical or microbial- is more difficult to remove? Justify your answer. (2 marks, 2025, Hardness of Water)
Unit 4 syllabus topics
- Hardness of Water
- Boiler Troubles
- Water Softening Techniques
- Calorific Value of Fuels
- Coal Analysis
- Biogas Production