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ScienceClass 8ICSE

What name is given to the cutting and gathering of a food crop like wheat or paddy?

Answer The cutting and gathering of mature food crops like wheat or paddy is known as harvesting.

ScienceClass 8ICSE

Which of the following is being used as a source of hydrogen gas needed to manufacture fertilizers? (a) Biogas (b) Natural gas (c) Coal gas (d) Petroleum gas

Answer (b) Natural gas

ScienceClass 8ICSE

The gas which occurs above the petroleum oil trapped under the rocks is called: (a) Biogas (b) Petroleum gas (c) Natural gas (d) Coal gas

Answer Petroleum gas

ScienceClass 8ICSE

Which is the major component of CNG? (a) Ethane (b) Propane (c) Methane (d) Butane

Answer Ethane

ScienceClass 8ICSE

The major component of LPG is: (a) Hydrogen (b) Carbon monoxide (c) Methane (d) Butane

Answer Butane

ScienceClass 8ICSE

Which one of the following is not a fossil fuel? (a) Petrol (b) Coke (c) Charcoal (d) Coal

Answer Charcoal

ScienceClass 8ICSE

(a) What are petrochemicals? Name any two petrochemicals. (b) Why are petro-chemicals so important?

Answer The other by-products are obtained from petroleum and are used These substances are called petrochemicals. Some of the petrochemicals are detergents, dyes, kerosene, etc. Petrochemicals are used in many fields and have a wide range of uses. Kerosene is used as a fuel in jet planes. Some of the products are used by the pharmaceuticals. Hence, it is an important substance across society, politics, technology including in economy

ScienceClass 8ICSE

(a) What is petroleum? Where does petroleum occur? (b) Describe the process of the formation of petroleum.

Answer (a) Petroleum is a naturally occurring element that is in a liquid state. It is either yellow or black in color. Petroleum is referred to as Black Gold. It is usually found in geological formations underneath the earth’s crust. When it is drilled from the ground in the liquid form, it is called crude oil. (b) Dead organisms that got buried in the sea millions of years ago got covered with layers of sand and clay. Due to lack of air, high temperature, and high pressure, these dead organisms got transformed into petroleum and natural gas.

ScienceClass 8ICSE

(a) What are fossil fuels? Name three fossil fuels. (b) Describe how, fossil fuels were formed.

(a) Fossil fuels are buried flammable geologic deposits of organic substances such as dead plants, and animals that got deposited under several thousand feet of silt. These deposits decayed with the passage of time and got converted to natural gas, coal, and petroleum due to the extreme heat and pressure inside the earth’s crust. They are also known as non-renewable sources of energy as it takes a very long time for it to replenish.

ScienceClass 8ICSE

(b) What is meant by exhaustible natural resources? Name any two exhaustible natural resources.

Answer Exhaustible sources are those sources of energy, which will deplete and exhaust after a few hundred years. Coal, petroleum, etc. are the exhaustible sources of energy. If all the exhaustible natural resources are exhausted by human activities then survival of living beings would be impossible. Fossil fuels are a very important source of energy for us today. On burning fossil fuel, it gives off heat and light. The heat produced can be used to cook food or to run engines such as automobile engines. It is also used to generate electricity as in powerhouse where the most common fuel used is coal.

ScienceClass 8ICSE

State (a) two uses of kerosene, and (b) two uses of paraffin wax.

Answer (i) Kerosene is used as a fuel for jets (ii) Kerosene is also used as fuel for airplanes (i) Paraffin wax is used to make candles and toys (ii) Paraffin wax is also used as a coating to keep fruits and vegetables fresh.

ScienceClass 8ICSE

What is meant by inexhaustible natural resources? Name two inexhaustible natural resources.

Answer An inexhaustible resource is a resource that never runs out or gets depleted. Some of such resources include wind, sun, solar energy, tides, and geothermal energy. They are mostly the naturally occurring resources hence they reappear naturally. These resources can be regenerated and can be utilized efficiently. The resources are available all over the world and they are easy to access.

ScienceClass 8ICSE

Why should we use fossil fuels only when absolutely necessary?

Answer Fossil fuel is a non-renewable resource and it takes millions of years to rebuild. The burning of fossil fuels is the main cause of air pollution. On burning, these produce harmful gases like carbon monoxide, sulfur dioxide, etc and cause global warming in the atmosphere. Then this leads to depletion of the ozone layer. Hence we should use fossil fuels only when absolutely necessary.

ScienceClass 8ICSE

What is the major cause of air pollution? Write the various tips for minimizing the wastage of petrol/diesel while driving vehicles.

Answer The burning of fossil fuels is the main cause of air pollution. On burning, these produce harmful gases like carbon monoxide, sulfur dioxide, etc and cause global warming in the atmosphere. Then this leads to depletion of the ozone layer. Tips for minimizing the wastage of vehicles: Drive the vehicle at a constant speed Switch off the vehicle’s engine at a traffic light Ensure correct air pressure in the tires of the vehicle

ScienceClass 8ICSE

State one use each of the following products of petroleum: (a) petroleum gas, (b) petrol, (c) Diesel, (d) Lubricating oil, (e) Bitumen

Answer LPG is used in households as well as in the Petrol is used as fuels for vehicles Diesel is generally preferred for heavy motor Lubricating oil reduces wear and tear and corrosion of Bitumen or asphalt is mainly used to surface

ScienceClass 8ICSE

(a) Where and when was the world’s first oil well drilled? (b) Where and when was oil first struck in India?

Answer (a) The world’s first oil well was drilled in Pennsylvania, USA, in 1859. (b) in 1867, oil was struck at Makum in Assam. In India, oil is found in Assam, Gujarat, Mumbai High, and in the river basins of Godavari and Krishna.

ScienceClass 8ICSE

Which material is called ‘black gold’? why?

Answer Petroleum is referred to as Black Gold. It is used to manufacture various products such as pharmaceuticals, plastics, gasoline, synthetic fabrics, etc so it is called black gold.

ScienceClass 8ICSE

What are the advantages of using LPG as fuel?

The advantages of using LPG as fuels are as follows LPG burns LPG gives a lot of heat energy when LPG can be transported easily through LPG are clean fuels and they do not release smoke when

ScienceClass 8ICSE

Name any five useful substances which are manufactured from petrochemicals.

Answer Useful substances which are manufactured from petrochemicals are Detergents, Dyes, Plastics, Paints, and some raw materials for pharmaceutical companies.

ScienceClass 8ICSE

Where is the natural gas found? Why is natural gas called a clean fuel?

Answer Natural gas is found in deep underground rock formations or near petroleum or coal reservoirs. It is called clean fuel because: It burns completely and produces 50% less CO2 gas than coal when burning Efficient combustion process Non-toxic and non-poisonous

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