Class 8 Science Chapter 3 Question Answers - Coal And Petroleum

Q1: Discuss importance of natural gas in our daily life.

Ans: Natural gas plays a crucial role in our daily lives as a significant fossil fuel. Its advantages include:

• Transportability: Natural gas is easily transported through pipelines.
• Storage: It can be stored under high pressure as Compressed Natural Gas (CNG), making it suitable for use in vehicles.
• Cleaner Fuel: CNG is less polluting compared to other fossil fuels, contributing to better air quality.
• Cost-Effective: Vehicles powered by CNG generally have lower maintenance costs.
• Sealed Systems: CNG fuel systems are sealed, preventing spills and evaporation losses.
• Industrial Use: Natural gas is also a key ingredient in the production of various chemicals and fertilisers.

In India, natural gas reserves are found in regions such as Tripura, Rajasthan, Maharashtra, and the Krishna Godavari delta.

Q2: Explain fossil fuels. 

Ans: Some exhaustible natural resources like coal, petroleum and natural gas are called fossil fuels as they are formed from the dead remains of living organisms (fossils). Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. The production and use of fossil fuels raise environmental concerns.
Coal: About 300 years ago the earth had dense forests in low lying wetland areas. Due to natural processes, like flooding these forests got buried under the soil. They get sank deeper and deeper and temperature gets increasing day by day, under high pressure and high temperature dead plants slowly got converted to coal. Coal's primary use is for the generation of electricity. It is also used in the industrial and retail sector as fuel for heating and powering foundries, cement plants and other industrial and manufacturing facilities.
Petroleum: Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years in absence of air and under high temperature and high pressure the dead organisms get transformed into Petroleum and natural Gas. Petroleum is a dark oily liquid. It has an unpleasant odour. It is a mixture of various constituents such as Petrol, Diesel, etc. and the process of separating these constituents from crude oil is called Refining.
Q3: Describe coal and its various products along with their uses. 

Ans: Coal is a hard and black coloured non-metal which is used to cook food, in the past it was also used to run railway engines, apart from this it is also used to produce electricity in thermal power plant; it is also used as fuel in various industries.
Following are the products of coal:
1. Coke: Coke is a product of coal; it is tough, porous, and black in colour and almost pure formof carbon. It is used in making steels and in extraction of many metals
2. Coal tar: Coal tar is the product of coal which is the mixture of various substances. Products obtained from coal tar is used for manufacturing a variety of products like dyes, drugs, perfumes, explosives, paints, photographic materials, roofing materials etc.
3. Coal gas: Coal gas is obtained during the processing of Coal to get coke. It is used as a fuel in many industries situated near the coal processing plants.

Q4: Write notes on wide and judicious use of our exhaustible natural resource. 

Ans: Exhaustible resources like coal, petroleum are formed from the dead organisms, it takes millions of years for formation of these fuels, and On the other hand the known reserves of these will last almost a few hundred years. A part from this since these products are not environmental friendly as burning of these fuels is a major cause of air pollution and their use is also linked to global warming therefore we should use these resources only when it is actually required. Wise use of natural resource will result in better environment, smaller risk of global warming and their availability for a longer period of time.
Q5: Write the names of various components of petroleum and write their uses.
Ans. The components of petroleum and their uses are as follows:

• LPG(Liquefied Petroleum Gas): Used as a domestic and industrial fuel.
• Petrol: Serves as motor fuel, aviation fuel, and a solvent for dry cleaning.
• Kerosene: Utilised as fuel for stoves, lamps, and jet aircraft.
• Diesel: Used in heavy motor vehicles and electric generators.
• Lubricating Oil: Acts as a lubricant.
• Paraffin Wax: Employed in making ointments, candles, and Vaseline.
• Bitumen: Used in the production of paints and for road surfacing.

Q6: What advise is given by PCRA for saving petrol and diesel?
 Ans. The Petroleum Conservation Research Association (PCRA) offers several tips to help save petrol and diesel:

• Drive at a constant and moderate speed whenever possible.
• Switch off the engine at traffic lights or when waiting.
• Maintain correct tyre pressure.
• Ensure regular maintenance of your vehicle.

By following these tips, you can save both fuel and money, contributing to national energy conservation.