Long answer questions
1. How are fuels classified on the basis of their physical state! Give at least two amples of each
2. What is a fire extinguisher? Explain its working
3. Mention the different methods by which a fire can be extinguished
4. Describe the different zones of a candle fame!
5. Differentiate between complete and incomplete combustion. Give their word equations
6. What do you mean by fuel efficiency! What role it plays in selection of fuel?
7. How acid rain is caused! Explain belly
Answers
Answer:
- On the basis of physical state of fuel they are classified into solid, liquid, gaseous state. Example: Solid:- ⟶ Wood, cowdung cakes and agricultural waste. Liquid:- Kerosene, diesel and petrol. Gaseous:- Biogas, CNG and LPG
- Water extinguishers work by removing heat from the fire. Dry chemical extinguishers are tanks of foam or dry powder with compressed nitrogen as the propellant. They work by smothering the fire: when you put a layer of powder or foam on the fire, you cut the fuel off from the oxygen around it, and the fire goes out
- The preferred method for extinguishing class “A” fires is to remove the heat. Water is the most common agent, but others such as dry chemical, halon, halogenated agents and foam can be used effectively. A class “B” fire involves flammable liquid or gas
4.A is non-luminous zone, B: Luminous zone and C: Dark Zone. Non-luminous zone is the zone of complete combustion. It is the hottest zone of the candle flame and does not produce much light. Middle zone is the zone which is moderately hot with limited supply of oxygen.
5.Complete combustion occurs when there is enough oxygen to completely use up all the reactants. Incomplete combustion occurs when there is not enough oxygen resulting in the production of smoke, and less energy is produced when compared with complete combustion.Incomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide. In general for incomplete combustion: hydrocarbon + oxygen → carbon monoxide + carbon + water. The carbon is released as soot .
6.Fuel efficiency is a form of thermal efficiency, meaning the ratio from effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work.
7.Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.
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