Term 3 · Class 8 Science · Chapter 6

Samacheer Class 8 Science - Chemistry in Everyday Life

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Chapter-wise textbook exercise answers for Chemistry in Everyday Life with validation-aware solutions.

Answers marked verified were checked during generation against the chapter context and source question text.
Sections in this chapter
I. Choose the best answer: 5II. Fill in the blanks: 1III. Match the following: 1IV. Answer briefly: 8V. Answer in detail: 3
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1I. Choose the best answer:5 questions
Q.1The chemical mixed with LPG that helps in the detection of its leakage is …………………v
  1. A. methanol
  2. B. ethanol
  3. C. camphor
  4. D. mercapton
Solution

(d) mercapton

Answer:

(d) mercapton

Q.2Which is known as syn gas?v
  1. A. Marsh gas
  2. B. Water gas
  3. C. Producer gas
  4. D. Coal gas
Solution

(b) Water gas

Answer:

(b) Water gas

Q.3The unit of calorific value of fuel is …………………v
  1. A. kilo joule per mole
  2. B. kilo joule per gram
  3. C. kilo joule per kilo gram
  4. D. joule per kilo gram
Solution

(c) kilo joule per kilo gram
SamacheerKalvi.Guru

Answer:

(c) kilo joule per kilo gram
SamacheerKalvi.Guru

Q.4………………… is the coal of superior quality.v
  1. A. Peat
  2. B. Lignite
  3. C. Bituminous
  4. D. Anthracite
Solution

(d) Anthracite

Answer:

(d) Anthracite

Q.5The main component of natural gas is …………………v
  1. A. methane
  2. B. ethane
  3. C. propane
  4. D. butane
Solution

(a) methane
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Answer:

(a) methane
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2II. Fill in the blanks:1 questions
Q.G1Producer gas is a mixture of ………….. ………….. is known as marsh gas. The term petroleum means ………….. Heating coal in the absence of air is called …………… An example for fossil fuel is …………..v
Solution

Carbon monoxide and nitrogen
Methane
Rock oil
Destructive distillation
Coal

Answer:

Carbon monoxide and nitrogen
Methane
Rock oil
Destructive distillation
Coal

3III. Match the following:1 questions
Q.1Octane rating –v
  1. (a) Diesel Cetane rating –
  2. (b) Methane Simplest hydrocarbon –
  3. (c) Petrol Peat –
  4. (d) Bown in colour Lignite –
  5. (e) First stage coal
Solution

c
a
b
e
d
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Answer:

c
a
b
e
d
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4IV. Answer briefly:8 questions
Q.1What do you mean by catenation?v
Solution

The property of carbon atom to form bonds with itself resulting in a single large structure or chain is called catenation.

Answer:

The property of carbon atom to form bonds with itself resulting in a single large structure or chain is called catenation.

Q.2Mention the advantages of natural gas.v
Solution

It produces lot of heat as it is easily burnt.
It does not leave any residue.
It bums without smoke and so causes no pollution.
This can be easily supplied through pipes.
It can be directly used as fuel in homes and industries.
SamacheerKalvi.Guru

Answer:

It produces lot of heat as it is easily burnt.
It does not leave any residue.
It bums without smoke and so causes no pollution.
This can be easily supplied through pipes.
It can be directly used as fuel in homes and industries.
SamacheerKalvi.Guru

Q.3Expand CNG. List out its uses.v
Solution

CNG – Compressed Natural Gas.
It is the cheapest and cleanest fuel.
Vehicles using this gas produce less carbon dioxide and hydrocarbon emission.
It is less expensive than petrol and diesel.

Answer:

CNG – Compressed Natural Gas.
It is the cheapest and cleanest fuel.
Vehicles using this gas produce less carbon dioxide and hydrocarbon emission.
It is less expensive than petrol and diesel.

Q.4Identify the gas known as syngas. Why is it called so?v
Solution

Water Gas is also called as syngas or synthesis gas as it is used to synthesize methanol and simple hydrocarbons. It is used as an industrial fuel also.

Answer:

Water Gas is also called as syngas or synthesis gas as it is used to synthesize methanol and simple hydrocarbons. It is used as an industrial fuel also.

Q.5Anthracite is known as the highest grade coal. Give reason.v
Solution

Anthracite is the highest grade coal.
It has a very light weight and the highest heat content.
Anthracite coal is very hard, deep black and shiny.
It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
It bums longer with more heat and less dust.
SamacheerKalvi.Guru

Answer:

Anthracite is the highest grade coal.
It has a very light weight and the highest heat content.
Anthracite coal is very hard, deep black and shiny.
It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
It bums longer with more heat and less dust.
SamacheerKalvi.Guru

Q.6Distinguish between octane number and cetane number.v
Solution

Octane Number:
Octane rating is used for petrol
It measures the amount of octane present in petrol
Octane number of petrol can be increased by adding benzene or toluene.
The fuel with high octane number has low cetane number
Cetane Number:
Cetane rating is used for diesel
It measures the ignition delay of the fuel in diesel engine.
Cetane number of diesel can be increased by adding acetone.
The fuel with high cetane number has low octane number

Answer:

Octane Number:
Octane rating is used for petrol
It measures the amount of octane present in petrol
Octane number of petrol can be increased by adding benzene or toluene.
The fuel with high octane number has low cetane number
Cetane Number:
Cetane rating is used for diesel
It measures the ignition delay of the fuel in diesel engine.
Cetane number of diesel can be increased by adding acetone.
The fuel with high cetane number has low octane number

Q.7Name the places in Tamilnadu harnessing wind energy from wind mills.v
Solution

Wind mills are mostly located at Kayathar, Aralvaimozhi, Palladam and Kudimangalam in Tamil Nadu.

Answer:

Wind mills are mostly located at Kayathar, Aralvaimozhi, Palladam and Kudimangalam in Tamil Nadu.

Q.8Solar energy is a non – depleting energy. Justify.v
Solution

Solar energy is the only viable fuel source of non – depleting nature for, Sun provides a free and renewable source of energy.
It is the renewable type of energy without endangering the environment.
It is the potential source to replace the fossil fuel in order to meet the needs of the world. With the advancements in science and technology, solar energy has become more affordable, and it can overcome energy crisis.
SamacheerKalvi.Guru

Answer:

Solar energy is the only viable fuel source of non – depleting nature for, Sun provides a free and renewable source of energy.
It is the renewable type of energy without endangering the environment.
It is the potential source to replace the fossil fuel in order to meet the needs of the world. With the advancements in science and technology, solar energy has become more affordable, and it can overcome energy crisis.
SamacheerKalvi.Guru

5V. Answer in detail:3 questions
Q.1Explain the different types of coal.v
Solution

Lignite:
Lignite is a brown coloured coal of lowest grade.
It has least content of carbon. The carbon content of lignite is 25 – 35%.
Lignite contains a high amount of water and makes up almost half of our total coal reserves.
It is used for electricity generation.
It is used to generate synthetic natural gas and produce fertilizer products.
Sub-bituminous:
When lignite becomes darker and harder over time, sub-bituminous coal is formed.
Sub-bituminous coal is a black and dull coal.
It has higher heating value than lignite and contains 35-44% carbon.
It is used primarily as fuel for electricity power generation.
This coal has lower sulfur content than other types and bums cleaner.
Bituminous:
With more chemical and physical changes, sub-bituminous coal is developed into bituminous coal.
It is dark and hard. It contains 45-86% carbon. It has high heating value.
It is used to generate electricity.
Other important use of this coal is to provide coke to iron and steel industries.
By-products of this coal can be converted into different chemicals which are used to make paint, nylon and many other items.
Anthracite:
It is the highest grade coal. It is hard and dark black in colour.
It has a very light weight and the highest heat content.
Anthracite coal is very hard, deep black and shiny.
It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
It bums longer with more heat and less dust.
SamacheerKalvi.Guru

Answer:

Lignite:
Lignite is a brown coloured coal of lowest grade.
It has least content of carbon. The carbon content of lignite is 25 – 35%.
Lignite contains a high amount of water and makes up almost half of our total coal reserves.
It is used for electricity generation.
It is used to generate synthetic natural gas and produce fertilizer products.
Sub-bituminous:
When lignite becomes darker and harder over time, sub-bituminous coal is formed.
Sub-bituminous coal is a black and dull coal.
It has higher heating value than lignite and contains 35-44% carbon.
It is used primarily as fuel for electricity power generation.
This coal has lower sulfur content than other types and bums cleaner.
Bituminous:
With more chemical and physical changes, sub-bituminous coal is developed into bituminous coal.
It is dark and hard. It contains 45-86% carbon. It has high heating value.
It is used to generate electricity.
Other important use of this coal is to provide coke to iron and steel industries.
By-products of this coal can be converted into different chemicals which are used to make paint, nylon and many other items.
Anthracite:
It is the highest grade coal. It is hard and dark black in colour.
It has a very light weight and the highest heat content.
Anthracite coal is very hard, deep black and shiny.
It contains 86-97% carbon and has a heating value slightly higher than bituminous coal.
It bums longer with more heat and less dust.
SamacheerKalvi.Guru

Q.2What is known as destructive distillation? Write about the products obtained from petroleum.v
Solution

Coal when heated in the absence of air does not bum but produces many by-products. This process of heating coal in the absence of air is called destructive distillation of coal.
Products obtained from petroleum:
Liquefied Petroleum Gas or LPG
Diesel and petrol
Kerosene
Lubricating oil
Paraffin
Bitumen or asphalt
Refinery Gas
Naphtha
Fuel Oil
Chemicals
Jet fuel
Waxes
Polishes

Answer:

Coal when heated in the absence of air does not bum but produces many by-products. This process of heating coal in the absence of air is called destructive distillation of coal.
Products obtained from petroleum:
Liquefied Petroleum Gas or LPG
Diesel and petrol
Kerosene
Lubricating oil
Paraffin
Bitumen or asphalt
Refinery Gas
Naphtha
Fuel Oil
Chemicals
Jet fuel
Waxes
Polishes

Q.3What are the different types of fuels?v
Solution

Fuels are classified into solid, liquid and gaseous fuels according to their physical state.
Solid fuels:
Fuels like wood and coal are in solid state and they are called solid fuels.
This type of fuel was the first one to be used by man.
These fuels are easy to store and transport.
The production cost is also very low.
Liquid fuels:
Most of the liquid fuels are derived from the fossil remains of dead plants and animals petroleum oil, coal tar and alcohol are some of the liquid fuels.
These fuels give more energy on burning and bum without ash.
Gaseous fuel:
Coal gas, oil gas, producer gas and hydrogen are some of the gaseous fuels.
It can be easily transported through pipes and they do not produce pollution.

Answer:

Fuels are classified into solid, liquid and gaseous fuels according to their physical state.
Solid fuels:
Fuels like wood and coal are in solid state and they are called solid fuels.
This type of fuel was the first one to be used by man.
These fuels are easy to store and transport.
The production cost is also very low.
Liquid fuels:
Most of the liquid fuels are derived from the fossil remains of dead plants and animals petroleum oil, coal tar and alcohol are some of the liquid fuels.
These fuels give more energy on burning and bum without ash.
Gaseous fuel:
Coal gas, oil gas, producer gas and hydrogen are some of the gaseous fuels.
It can be easily transported through pipes and they do not produce pollution.