Samacheer Kalvi 8th Science Solutions Chapter 15 Pdf
Tamilnadu Board Samacheer Kalvi 8th Science Solutions Chapter 15: Tamilnadu State Board Solution Class 8 Science Chapter 15 – Chemistry in Everyday Life.
Samacheer Kalvi 8th Science Solutions Chapter 15: Overview
|
Board |
Samacheer Kalvi |
| Class |
8 |
|
Subject |
Science |
| Chapter |
15 |
|
Chapter Name |
Chemistry in Everyday Life |
Samacheer Kalvi 8th Science Solutions Chapter 15 Pdf
(I) Choose the best answer.
(1 ) The chemical mixed with LPG that helps in the detection of its leakage is mercapton
a ) methanol
b) ethanol
c) camphor
d) mercapton
(2) Which is known as syn gas?
a) Marsh gas
b) Water gas
c) Producer gas
d ) Coal gas
(3) The unit of calorific value of fuel is KJkg-1.
a) KJmol- 1
b) KJg-1
c) KJkg -1
d) Jkg-1
(4) Anthracite is the coal of superior quality .
a) Peat
b) Lignite
c) Bituminous
d) Anthracite
(5) The main component of natural gas is methane.
a) methane
b) ethane
c) propane
d) butane
( II) Fill in the blanks .
1 ) Producer gas is a mixture of carbonmonoxide and nitrogen.
2 ) Methane is known as marsh gas.
3) The term petroleum means rock oil.
4) Heating coal in the absence of air is called destructive distillation.
5) An example for fossil fuel is coal.
( III) Match the following.
| Octane rating | Diesel |
| Cetane rating | Methane |
| Simplest hydrocarbon | Petrol |
| Peat | Brown in colour |
| Lignite | First stage coal |
Answer
| Octane rating | Petrol |
| Cetane rating | Diesel |
| Simplest hydrocarbon | Methane |
| Peat | First stage coal |
| Lignite | Brown in colour |
( IV) Answer briefly .
1 ) What do you mean by catenation?
The capability of the hydrocarbons to make bonds with each other. This property is called catenation, which means chain formation. Therefore, this property enables them to form greater number of complex molecules.
2) Mention the advantages of natural gas.
The advantages of natural gas are as follows :
- As it can be burnt easily, due to this reason it produces tremendous amount of heat.
- No residues are left by this gas.
- As no harmful gases are produced by natural gas and it also does not have any smoke, for this reason it is environmental friendly and does not cause any pollution.
- With the help of pipes, this gas can be easily supplied.
- It can be used as fuel not only in homes but also in industries.
3) Expand CNG. List out its uses.
The compression of the natural gas at a relatively high pressure is known as Compressed Natural Gas (CNG). In present times, several automobiles makes use of this gas as fuel. Methane is the primary hydrocarbon that is present in CNG.
The uses of CNG are as follows:
- CNG is considered as one of the cleanest fuel and it is also budget friendly.
- Vehicles making use of this gas generates less carbon dioxide and there is also a considerable reduction in hydrocarbon emission.
- This gas is quite inexpensive in comparison to petrol and diesel.
4) Identify the gas known as syngas . Why is it called so?
Water gas refers to a gaseous mixture of carbon monoxide and hydrogen. It is prepared at a temperature of 1000°C, by passing steam over incandescent coke. As it is used for the purpose of synthesizing methanol and simple hydrocarbons, for this reason water gas is also known as syngas or synthesis gas. Industries makes use of this gas as fuel.
5) Anthracite is known as the highest grade coal. Give reason.
Anthracite is considered as one of the highest grade coal. This coal is not very heavy and it also possess greatest heat content. Anthracite coal is deep black and shiny in colour and it also depicts sufficient hardness. This coal is composed of 86 to 97% of carbon and possesses a slightly higher heating value in comparison to bituminous coal. As it burns for quite a longer period of time, due to this reason it produces more heat. It also does not produce much dust at the time of burning
6) Distinguish between octane number and cetane number.
Octane Number
- Octane rating is mainly used for the purpose of petrol.
- Its primary function is to measure the quantity of octane contained in petrol.
- An addition of benzene or toluene can help in increasing the octane number of petrol.
- The fuel which contains low cetane number, usually has a high octane number.
Cetane Number
- Cetane rating is mainly used for the purpose of diesel.
- In diesel engine, the ignition delay of the fuel is measured by cetane number.
- An addition of acetone can contribute in increasing the cetane number of diesel.
- The fuel which consists low octane number ,usually has high cetane number.
7 ) Name the places in Tamil Nadu harnessing wind energy from wind mills.
Kayathar, Aralvaimozhi, Palladam and Kudimangalam are for instance, several places in Tamil Nadu where most of the wind mills are located.
8) Solar energy is a non depleting energy. Justify.
Sun acts as a major source of energy, that facilitates the existence of life on the earth. As, sun plays an essential role in providing free and renewable source of energy, due to this reason solar energy is considered as the only viable fuel source of non depleting nature. As, it is a renewable source of energy ,so it does not pose any harmful effects to the environment. In order to fulfill the requirements of the world, it acts as a potential source by replacing the fossil fuel. The progression in science and technology has contributed in making solar energy more reasonable and it can also perform an essential role in overcoming energy crisis. Solar energy is considered as a clean energy. Hence, maximum energy can be utilised by using various equipment’s, were only a minimal amount of effort is required.
( V) Answer in detail.
1 ) Explain the different types of coal.
Lignite, sub -bituminous, bituminous and anthracite are mainly the four different types of coal that are classified on the basis of carbon content and production of heat energy.
Lignite
Lignite is considered as the lowest grade coal and it is brown in colour. Lignite contains 25 to 35% of carbon, which clearly signifies a lower carbon content. Lignite consists an ample quantity of water and constitutes half of our total coal reserves. It is not only used for generating electricity and synthetic natural gas but it is also used in the production of fertilizer products.
Sub – bituminous
When lignite turns darker and harder over a period of time, then it leads to the formation of sub – bituminous coal. This coal is dull and blackish in colour. The carbon content of this coal is 35 to 44%. It possess greater heating value in comparison to lignite .
Bituminous
Sub – bituminous coal is transformed into bituminous coal, with the occurrence of several chemical and physical changes. Bituminous coal depicts sufficient hardness and it is dark in colour. The carbon content of this coal is 45 to 86% . It also possess greater heating value. It is not only used for generating electricity but it is also used for supplying coke to iron and steel industries. After converting the by -products of this coal into several different chemicals, they can be used for the purpose of manufacturing paint, nylon and numerous other products.
Anthracite
Anthracite is considered as one of the highest grade coal. This coal is not very heavy and it also possess greatest heat content. Anthracite coal is deep black and shiny in colour and it also depicts sufficient hardness. This coal is composed of 86 to 97% of carbon and possesses a slightly higher heating value in comparison to bituminous coal. As it burns for quite a longer period of time, due to this reason it produces more heat. It also does not produce much dust at the time of burning
2) What is known as destructive distillation? Write about the products obtained from fractional distillation of petroleum.
Destructive distillation refers to the process in which the coal is heated without the presence of air.Heating coal without the presence of the air, does not support burning and it also gives rise to numerous by – products.
The products that are acquired from fractional distillation of petroleum are as follows:
- Refinery Gas
- Petrol
- Naphtha
- Kerosene
- Diesel
- Lubricating oil
- Fuel oil
- Residue
The uses of petroleum are as follows:
- Both houses and industries makes use of Liquefied Petroleum Gas ( LPG) .
- In vehicles, diesel and petrol are used as fuels. It is also used for operating electric generators.
- For the purpose of dry cleaning, petrol is used as a solvent.
- Kerosene is not only used as a fuel for stoves but it is also used as a jet fuel.
- Lubricating oil helps in decreasing wear and tear and protects the machines from corrosion.
- Paraffin wax is used for the purpose of making candles, ointments, ink and crayons.
- For surfacing roads, bitumen is used to a considerable extent.
3) Explain the different types of fuel gases.
Producer Gas
Producer gas refers to a gaseous mixture of carbon monoxide and nitrogen. It is prepared at a temperature of 1100° C , by passing a mixture of air and steam over red hot coke. It is used as an industrial fuel for the purpose of manufacturing iron and steel.
Coal gas
Hydrogen, methane and carbon monoxide are for instance, a mixture of gases that are acquired by the destructive distillation of coaland these gases are known as coal gas. Destructive distillation refers to a process in which the coal is heated without the presence of air. In the process of manufacturing steel, an open hearth furnace is heated by using this gas.
Water Gas
Water gas refers to a gaseous mixture of carbon monoxide and hydrogen. It is prepared at a temperature of 1000°C, by passing steam over incandescent coke. As it is used for the purpose of synthesizing methanol and simple hydrocarbons, for this reason water gas is also known as syngas or synthesis gas. Industries makes use of this gas as fuel.
Bio- Gas
A mixture of methane and carbon dioxide constitutes a gas, which is known as biogas. It is prepared by decomposing the organic waste of plants and animals which constitutes the organic materials. Biogas is formed when an organic matter is broken down in the absence of oxygen. It is one of the most relevant example of renewable source of energy.
