Engineering Chemistry Unit 4 – Water Technology and Fuels: AKTU previous year questions
46 AKTU questions from Unit 4 (Water Technology and Fuels) asked in 2021–2026, tagged by marks, year and topic. In short: about 26 marks of every paper come from this unit; the most asked topic is Water Softening Techniques (16 times); 38 questions came back in a later year. The latest ones are listed below; on the page you can filter them by 2-mark or long questions, topic and repeats.
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)
- 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)
- Compare Ion Exchange process and Zeolite process for water softening. Under what conditions is each process preferred? (7 marks, 2026, Water Softening Techniques)
- 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)
- 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)
- Calculate the hardness of water sample containing impurity of Ca(HCO3)2 81 mg/l. Give your answer in °F also. (2 marks, 2025, Hardness of Water)
- 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)
- Why is natural gas preferred over coal for power generation, even though coal is more abundant? Two coal samples have identical fixed carbon content but different volatile matter percentages. How will this affect their combustion properties? (7 marks, 2025, Coal Analysis)
- Explain the different parameters that are determined in the proximate analysis of coal. On burning 0.92g of a solid fuel in a bomb calorimeter, the temperature of 3300g of water increased by 2.42°C. Water equivalent of calorimeter and latent heat of steam are 385.0g and 587.0cal/g, respectively. If the fuel contains 0.7% hydrogen, calculate its GCV and NCV. (7 marks, 2025, Calorific Value of Fuels)
- Why is the Zeolite process unsuitable for water containing high concentrations of iron and manganese? A 500 L water sample requires 50 mL of 0.01 M EDTA to completely react with its calcium and magnesium ions. Calculate the total hardness in ppm as CaCO3. (7 marks, 2025, Water Softening Techniques)
Most asked Unit 4 topics
- Water Softening Techniques – asked 16 times
- Calorific Value of Fuels – asked 15 times
- Coal Analysis – asked 6 times
Unit 4 question pattern
- 2-mark questions: 16 asked in 2021–2026
- 7-mark questions: 21 asked in 2021–2026
- 10-mark questions: 9 asked in 2021–2026
- About 26 marks from Unit 4 in every paper
- 38 questions were asked again in a later year
Unit 4 questions year by year
- 2026: 5 Unit 4 questions asked (25 marks across that year's papers)
- 2025: 9 Unit 4 questions asked (48 marks across that year's papers)
- 2024: 8 Unit 4 questions asked (46 marks across that year's papers)
- 2023: 9 Unit 4 questions asked (48 marks across that year's papers)
- 2022: 10 Unit 4 questions asked (68 marks across that year's papers)
- 2021: 5 Unit 4 questions asked (34 marks across that year's papers)