SPARTAN INTERNATIONAL SENIOR SECONDARY SCHOOL
CHEMBARAMBAKKAM, CHENNAI – 600 056
SUBJECT: SCIENCE
GRADE :8
CHAPTER:3/CAOL AND PETROLEUM
I.ANSWER THE FOLLOWING:
1.Describe how coal is formed from dead vegetation. What is this process called?
Answer:
Millions of years ago, trees, plants, ferns and forests got buried below the rocks, soil and sand
due to natural processes like flooding, earthquake, etc. Slowly, as more soil deposited over them,
they were compressed. This led to the conditions of high pressure and heat. These conditions
along with the anaerobic conditions turned the carbon-enriched organic matter of wood into coal.
This slow process of conversion of wood into coal is called carbonisation.
2. Explain the process of the formation of petroleum.
Answer:
Petroleum is formed by the burial of aquatic plants and animals below the sea bed. The marine
animals and plants died thousands of years ago and settled down in the bottom of sea. In
anaerobic conditions, microorganisms decompose this organic matter. Due to high pressure and
heat, the dead remains of tiny plants and animals were slowly converted into petroleum.
3. Sunlight and air are inexhaustible natural resources. Comment.
Answer:
Natural resources which are inexhaustible are those whose quantity is not based on consumption
or is not subject to scarcity. The amount of sunlight and air available is unaffected by human
consumption. This is why these natural resources are inexhaustible.
4. Define the term ‘petrochemicals’.
Answer:
Petrochemicals are the substances obtained from petroleum and natural gas. They are used in the
manufacture of detergents, fibres, polythene, etc.
5.What is CNG? What are its uses?
Answer:
CNG is 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.
II. ANSWER IN BRIEF:
1. : We say fossil fuels will last only for a few hundred years. Comment.
Answer:
The creation of fossil fuels takes a very long time. It also requires special circumstances, which
aren’t common. As a result, their limited supply will only endure a few hundred years. Fossil
fuels are exhaustible resources. Nature has a limited supply of these resources. Human activities
have the potential to deplete them. Forests, wildlife, minerals, coal, petroleum, natural gas, and
other resources are examples of these resources.
Petroleum and coal are both fossil fuels. It took millions of years for dead organisms to be turned
into these fuels. The known reserves of these, on the other hand, will last only a few hundred
years. Furthermore, the burning of these fuels contributes significantly to air pollution. Their use
contributes to global warming. As a result, we should only use these fuels when absolutely
required. As a result, the environment will be improved, the risk of global warming will be
reduced, and they will be available for a longer length of time.
2.We read in newspapers that burning of fuels is a major cause of global warming. Explain why.
Answer:
The use of fossil fuels in many regions has resulted in significant air pollution. Sulphur dioxide,
carbon dioxide, and other hazardous gases are produced when fossil fuels are burned. The gases
that vehicles, power plants, companies, residences, and other sources of pollution produce assist
to raise the temperature of the environment and the earth by heating the atmosphere and air.
3. Name the products obtained and their uses when coal is processed in industry.
Answer:
During coal processing, the following items are produced:
Coal tar is used to make synthetic pharmaceuticals, explosives, fragrances, paints, and plastics,
among other things.
Coke is a substance that is used to make steel and extract metals.
Coal gas is a fuel that is used in industry.
III: ANSWER IN DETAIL:
1. : Some natural resources are given in a box. Classify them into the exhaustible and
inexhaustible natural resources.
air, coal, natural gas, sunlight, petroleum, minerals, forests, oxygen.
Answer:
Exhaustible resources are coal, natural gas, petroleum, minerals, forests.
They are in limited supply and are being depleted by human activity.
These resources can’t be replenished once they’ve been depleted.
Non-renewable or non-replenishable resources are those that cannot be replenished.
They, like iron and coal, require conservation measures to ensure that they can be used in
the future.
Inexhaustible resources are air, sunlight, oxygen.
They exist in an infinite supply and cannot be depleted by human activity.
These resources have the power to regenerate themselves over time.
These are resources that can be replenished or are renewable.
They do not require conservation measures because they can be renewed, such as sunlight
and water.
2.List the steps to conserve the resources.
Answer:
Steps to conserve resources:
We should 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.
3. Write some important uses of the various constituents of petroleum.
Answer:
Constituents of petroleum Uses
Petroleum Gas in Liquid form
(LPG) Fuel for home and industry
Motor fuel, aviation fuel, solvent for
Petrol dry cleaning
Fuel for stoves, lamps and for jet
Kerosene aircrafts
Fuel for heavy motor vehicles, electric
Diesel generators
Lubricating oil Lubrication
Paraffin wax Ointments, candles, Vaseline etc.
Bitumen Paints, road surfacing
