Question 1: Combustion is a chemical process in which a substance reacts rapidly with oxygen, producing heat and light. It is a common way to release energy from fuels such as petrol, kerosene, and natural gas.

Answer: Combustion is a chemical reaction where a substance reacts with oxygen, producing heat and light.

Question 2: List three common products formed during complete combustion of hydrocarbon fuels.

Answer: Carbon dioxide, water, and energy (heat/light).

Question 1: What is the main difference between complete and incomplete combustion?

Answer: Complete combustion produces only carbon dioxide and water, while incomplete combustion produces carbon monoxide, soot, or other pollutants.

Question 2: Why does incomplete combustion occur more often in poorly maintained engines?

Answer: Because there is insufficient oxygen for complete combustion, leading to the formation of carbon monoxide and soot.

Question 1: Calculate the amount of carbon dioxide produced when 16 grams of methane (CH4) undergoes complete combustion. (Molar mass of CH4 = 16 g/mol, CO2 = 44 g/mol)

Answer: 11 g of CO2

Question 2: If 100 grams of propane (C3H8) are burned completely, how much energy is released? (Given: Energy released per mol of C3H8 = 2220 kJ, molar mass of C3H8 = 44 g/mol)

Answer: 5055 kJ

Question 1: Describe a simple experiment to demonstrate complete combustion of a hydrocarbon. Include safety precautions.

Answer: Light a clean, controlled flame of a hydrocarbon fuel (like a candle or Bunsen burner with methane). Ensure proper ventilation, keep flammable materials away, and use safety goggles. Observe the blue flame indicating complete combustion, where fuel reacts fully with oxygen to produce carbon dioxide and water.

Question 2: Identify the variables in an experiment testing the effect of oxygen supply on the completeness of combustion.

Answer: Independent variable: Amount of oxygen supplied. Dependent variable: Completeness of combustion (e.g., color of the flame). Control variables: Type of fuel, temperature, and amount of fuel used.

Question 1: A car engine burns petrol and releases pollutants such as carbon monoxide and soot. Explain how incomplete combustion contributes to pollution and suggest measures to reduce it.

Answer: Incomplete combustion produces harmful pollutants like carbon monoxide and soot, which can cause health issues and environmental damage. To reduce pollution, engines should be properly maintained for complete combustion, use of catalytic converters can help, and alternative cleaner fuels can be utilized.

Question 2: In industry, how is understanding of combustion principles important for energy production and environmental protection?

Answer: Understanding combustion helps optimize energy production by ensuring efficient fuel use, minimizing pollutants, and designing cleaner technologies like cleaner burners and pollution control devices, thus balancing energy needs with environmental protection.