Coal and Petroleum For Class 8 Science Extra Question Answer

Q 1 –  Name some renewable sources of energy.

Ans. Water, wind, solar.

Q 2 – Name the elements present in coal.

Ans. Carbon, oxygen and sulphur.

Q 3 – Give some examples of fossil fuels.

Ans. Coal, petroleum, natural gas.

Q 4 – Which are the two main techniques of mining?

Ans. Surface mining and underground mining.

Q 5 – List four varieties of coal.

Ans. Peat, lignite, bituminous, anthrac

Q 6 – Name the process of conversion of wood into coal.

Ans. Carbonisation

Q 7 – Mention the temperature at which destructive distillation is done.

Ans. 1000°C

Q 8 – When the crude oil is referred to be ‘sweet’?

Ans. If the sulphur content is low.

Q 9 – ‘Name the process of conversion of kerogen into gaseous hydrocarbons.

Ans. Catagenesis

Q 10 – Name the country which is the leading producer of petroleum.

Ans. Saudi Arabia

Q 11 – Name the gas that occurs over petroleum in reservoirs deep inside the earth.

Ans. Natural gas

Q 12 – Expand PCRA.

Ans. Petroleum Conservation Research Association.

Q 13 – What kind of pollution is caused by the burning of fossil fuels?

Ans. Air pollution

Q 14 – Which gas is produced when coal is burnt in air?

Ans. Carbon dioxide

Q 15 – Name the places where natural gas is found in our country.

Ans. Tripura, Rajasthan, Krishna Godavari Delta, Maharashtra, etc.

Q 16 – Define fossil fuels. Give examples.

Ans. Natural fuels that are made up by burial of living organisms under deep down the earth for over a long period of time are called fossil fuels. For example, coal, petroleum, natural gas.

Q 17 – Explain about coal tar.

Ans. It is produced when the gases are evolved due to the heating of coal in water. It is a black coloured, thick, viscous liquid. It has a pungent smell. It is itself a mixture of many compounds. We can get benzene, toluene, napthalene, phenol, etc., from coal tar.

Q 18 – Name two products that you obtain from the destructive distillation of coal. What is the residue left in’ this process? Give one main use of this residue.

Ans. The two important products obtained from the destructive distillation of coal are Coal gas and coal tar. The residue left in this process is coke. Coke is used mainly as a reducing agent in the extraction of metals.

Q 19 – What is CNG? What are its uses?

Ans. CNG is a short form of Compressed Natural Gas. Natural gas is stored under high pressure as CNG. CNG is used for power generation. It is now being used as a fuel for transport vehicles because it is less polluting. It is a cleaner fuel.

Q 20 – Explain the varieties of coal.

Ans. Depending upon the amount of carbon content, coal may be of four types:

  • Peat: This is the most inferior and softest form of coal. Its carbon content is very low. It has a large amount of moisture and is not much suitable to be used as fuel.
  • Lignite: Lignite is comparatively harder than peat, but still is very soft. Its carbon content is more than that of peat.
  • Bituminous: Its carbon content is higher, as it is free from moisture and other impurities.
  • Anthracite: This is the highest grade coal. This is also known as hard coal. It has maximum amount of carbon. It produces a very little smoke.

Q 21 – None of the fuels is a clean fuel. Comment.

Ans. On burning, every fuel releases at least CO2 which causes the greenhouse effect. Thus none of the fuels are clean.

Q 22 – Can forests help reduce the pollution caused by burning of fossil fuels? How?

Ans. Not all, but yes it reduces some of the pollutions like carbon dioxide emitted during the burning of fossil fuels.

Q 23 – What other source of energy may be used to drive vehicles?

Ans. Biodiesel, ethanol, solar energy.

Q 24 – What is coal? Write its two uses.

Ans. Coal is a hard, black combustible substance that mainly contains carbon.
Uses:

  • It is used as a fuel in homes and industry.
  • It is used as a fuel at Thermal Power Plants for generating electricity.

Q 25 – Name three constituents of petroleum and write their uses also.

Ans. The three constituents of petroleum are:

  • petrol
  • paraffin wax
  • diesel

Uses:

  • Petrol: It is used as a motor fuel and for dry cleaning.
  • Paraffin wax: It is used for making ointments, candles, vaseline, etc.
  • Diesel: It is used as a fuel for heavy motor vehicles and electric generators

Q 26 – Explain about coal tar.

Ans. It is produced when the gases are evolved due to the heating of coal in water. It is a black-coloured, thick, viscous liquid. It has a pungent smell. It is itself a mixture of many compounds. We can get benzene, toluene, napthalene, phenol, etc., from coal tar.

Q 27 – The burning of fossil fuels causes air pollution. Explain.

Ans. The burning of fossil fuels causes a lot of air pollution.
The burning of coal produces gases like carbon dioxide, carbon monoxide, sulphur dioxide, etc., which can lead to undesirable changes in climate due to the increased greenhouse effect.

The major air pollutants produced by the burning of petrol in automobiles are carbon monoxide, sulphur dioxide, unburnt hydrocarbons, etc. These pollutants are harmful to human beings and living organisms which causes breathing problems and skin diseases.

Q 28 – Write a short note on petroleum.

Ans. Petroleum is the liquid form of fuel. It is also known as crude oil and is found trapped between the layers of impervious rocks under the ground. It is a natural resource, formed by the dead plants and animals in the sea. It is a dark coloured viscous liquid and like all other oils, it is lighter than water. It is a mixture of different hydrocarbons. It undergoes fractional distillation to yield petrol, kerosene, diesel and other chemicals used in manufacture of plastics.

Q 29 – Find out the location of major thermal power plants in India. What could be the reasons for their being located at those places?

Ans. Major thermal power plants in India are located in Uttar Pradesh, Gujarat, West Bengal, Odisha, Chhattisgarh and Madhya Pradesh. The reason for their being located at those places is the presence of a majority of coal mines nearer to them.

Q 30- – Where and when was the first oil well drilled?

Ans. Pennsylvania, the USA in 1859.

Q 31 – How is the energy useful to us? Explain.

Ans. We need energy in almost every field of our life. Without energy our life is impossible.

Some of the uses of energy are:

  • We need energy of fuels to generate electricity and to run vehicles.
  • We need energy to run our electrical appliances like refrigerator, TV, radio, computer, etc.
  • We need energy at construction sites to construct houses, buildings, etc.
  • We need energy to cook our food and other domestic use.
  • We need energy (petrochemicals) for manufacturing fibres, plastics, paints, cosmetics, etc.
  • All the factories, industries, agricultural devices depend on power supply to run the machines.

Q 32 – ist the steps to conserve the resources.

Ans. As we know, we all are dependent on resources. But we should keep in mind that resources are limited in nature. If we misuse it, our future generation will have no resources. This is an alarming situation.
We can take the following steps:

  • We shbuld cook our food on low flame.
  • Devices that consume less energy like CFLs and LED lights should be preferred.
  • We should take care not to waste electricity.
  • We should cover our cooking vessels while cooking.
  • Instead of use of individual vehicles, use of public transport should be encouraged.
  • Solar or tidal energy should be developed and encouraged.
  • Dams should be use to generate electricity instead of burning coal or petroleum.
  • Public awareness programmes should be conducted.

Q 33 – You are provided with a mixture of petroleum and water. How will you separate the two?

Ans. Allow standing the mixture of petroleum and water undisturbed for some time. The top layer will have consisted of petroleum which can be separated from water by decantation.