In ECET Chemistry, Fuels & Calorific Value is one of the most frequently asked topics. Direct theory and numerical-based questions are expected from this unit. By mastering this, students can confidently secure 2–3 marks in Chemistry.
Concept Notes
🔥 Fuels
- Definition: Substances that produce heat and energy on combustion.
- Types of Fuels:
- Solid Fuels: Coal, wood, coke.
- Liquid Fuels: Petrol, diesel, kerosene.
- Gaseous Fuels: LPG, CNG, coal gas, producer gas.
⚡ Characteristics of Good Fuel
- High calorific value.
- Moderate ignition temperature.
- Easy availability and cheap.
- Safe storage and transport.
- Non-toxic and pollution free.
⚙️ Calorific Value
- Definition: The amount of heat energy produced when 1 gram (or 1 kg) of fuel is completely burnt.
- Formula:
latexlatexlatex Calorific , Value , (CV) = \frac{Heat , produced}{Mass , of , fuel} /latex/latex/latex - Units:
- SI unit → kJ/kg
- Also expressed as kcal/kg
- Example values:
- Wood → 17000 kJ/kg
- Coal → 33000 kJ/kg
- Petrol → 45000 kJ/kg
- LPG → 55000 kJ/kg
🔟 10 Most Expected MCQs – ECET 2026
Q1. Which of the following is a gaseous fuel?
A) Petrol
B) Diesel
C) LPG
D) Kerosene
Q2. The calorific value of a fuel is expressed in:
A) kJ/mol
B) kJ/kg
C) J/s
D) kg/m³
Q3. Which has the highest calorific value?
A) Coal
B) Wood
C) LPG
D) Kerosene
Q4. A good fuel must have:
A) Low calorific value
B) High ignition temperature
C) High calorific value
D) High ash content
Q5. The calorific value of coal is about:
A) 17000 kJ/kg
B) 33000 kJ/kg
C) 45000 kJ/kg
D) 55000 kJ/kg
Q6. Producer gas is a mixture of:
A) CO + N₂
B) CO₂ + H₂
C) CH₄ + CO₂
D) H₂ + O₂
Q7. Which is a solid fuel?
A) LPG
B) CNG
C) Coal
D) Petrol
Q8. Ignition temperature of a good fuel should be:
A) Very low
B) Very high
C) Moderate
D) Zero
Q9. The calorific value of petrol is approximately:
A) 17000 kJ/kg
B) 33000 kJ/kg
C) 45000 kJ/kg
D) 55000 kJ/kg
Q10. Which one is not a characteristic of a good fuel?
A) High calorific value
B) Easy storage
C) High cost
D) Safe transport
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | C |
| Q2 | B |
| Q3 | C |
| Q4 | C |
| Q5 | B |
| Q6 | A |
| Q7 | C |
| Q8 | C |
| Q9 | C |
| Q10 | C |
🧠 Explanations of All Answers
- Q1 → C: LPG is a gaseous fuel.
- Q2 → B: Calorific value is always expressed in kJ/kg.
- Q3 → C: LPG has the highest calorific value (~55000 kJ/kg).
- Q4 → C: A good fuel should have high calorific value.
- Q5 → B: Coal’s calorific value ≈ 33000 kJ/kg.
- Q6 → A: Producer gas = CO + N₂.
- Q7 → C: Coal is a solid fuel.
- Q8 → C: Moderate ignition temperature is safe and efficient.
- Q9 → C: Petrol ≈ 45000 kJ/kg.
- Q10 → C: High cost is not a good property.
🎯 Motivation / Why Practice Matters
Fuels & Calorific Value questions are direct memory-based in ECET.
By practicing these, students can confidently secure 2–3 marks in Chemistry.
Also, this concept is useful in real-life energy engineering and competitive exams.
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