Rbse Solutions for Class 8 Science Chapter 18 Carbon and Fuel

Board	RBSE
Class	Class 8
Subject	Science
Chapter	Chapter 18
Chapter Name	Carbon and Fuel
Number of Questions Solved	39
Category	RBSE Solutions

Carbon and Fuel Textbook Questions Solved

I. Multiple Choice Questions

Question 1.

1. The coal in which carbon content is highest
   (a) Peat
   (b) Lignite
   (c) Anthracite
   (d) Bituminous
2. The residue of fractional distillation of petroleum is
   (a) Lubricant oil
   (b) Wax
   (c) Coal tar
   (d) Diesel
3. The crystalline allotrope of carbon is-
   (a) Coal
   (b) Kajal
   (c) Charcoal
   (d) Graphite

Answers:

1. (c)
2. (c)
3. (d)

Question 2.
Fill in the blanks

1. …………….is the domestic liquid fuel.
2. In graphite each carbon atom is attached to…………….nearest carbon atoms while in
   diamond each carbon atom is attached to…………….nearest carbon atoms.
3. …………….is necessary for combustion.

Answers:

1. LPG
2. three, four
3. Oxygen

Question 3.
Put True (T) for correct and False (F) for incorrect for the following.

1. The carbon content in Lignite is 67%.
2. Peat coal is an example of liquid fuel.
3. Lubricant oil is used as fuel in vehicles and kitchen.
4. The crystalline allotropes of carbon are diamond, graphite and fullerin.

Answers:

1. (T)
2. (F)
3. (F)
4. (T)

Carbon and Fuel Short Answer Type Questions

Question 1.
Write the uses of petroleum gas.
Answer:
It is mainly useful as fuel in kitchen as cooking gas and automobiles.

Question 2.
We should sensibly use petrol and diesel like substances. Explain why?
Answer:

1. A long process and time is needed to form oxide oil or natural fuels.
2. Their deposits are limited only for next 100 years. ‘
3. They cause air pollution.
4. They help in global warming.

Question 3.
Write differences between diamond and graphite.
Answer:

S.No.	Properties	Graphite	Diamond
(i)	Hard/Soft	It is a hazy/ opaque sub­stance on touch. It is smooth and slippery.	Transparent, hard easily cracks.
(ii)	Structure	In graphite carbon atom on same surface joins three carbon and form a hexagonal structure. Such surface are bonded with weak bonds hence they can slide on each other. So, they are soft.	In diamond it joins with other nearest four carbons and forms a hard three dimensional structure.
(iii)	Electricity Conduction	It is good conductor of electricity.	It is bad conductor of electricity but good conductor of heat.
(iv)	Use	It is used in electric arc and dry cells.	It is used in jewellery, cutting, grinding, hole passing etc.

Question 4.
Compare L.P.G and Wood as Fuel.
Answer:

LPG	Wood
(i)	It gives more heat in less time.	(i) It gives less heat in more time.
(ii)	It causes less air pollution.	(ii) It causes air pollution.
(iii)	It bums completely.	(iii) It burns incompletely.
(iv)	It doesn’t produces ash.	(iv) It produces ash.

Question 5.
Name five compounds of carbon.
Answer:
Petrol, diesel, kerosene, wood and coal

Carbon and Fuel Long Answer Type Questions

Question 1.
Draw a well labelled diagram of diamond and graphite and explain their difference.
Answer:

S.No.	Properties	Graphite	Diamond
(i)	Hard/Soft	It is a hazy/opaque substance on touch. It is smooth and slippery.	Transparent, hard easily cracks.
(ii)	Structure	In graphite carbon atom on same surface joins three carbon and form a hexagonal structure. Such surface are bonded with weak bonds hence they can slide on each other. So, they are soft.	In diamond it joins with other nearest four carbons and forms a hard three dimensional structure.
(iii)	Electricity Conduction	It is good conductor of electricity.	It is bad conductor of electricity but good conductor of heat.
(iv)	Use	It is used in electric arc and dry cells.	It is used in jewellery, cutting, grinding, hole passing etc.

Question 2.
Write your views in the following table and also discuss with other students.
Answer:

Advantages of uses of petroleum as fuel	Disadvantages of uses of petroleum as fuel
Advantages of uses of petroleum as fuel	Disadvantages of uses of petroleum as fuel
Petroleum is used as a fuel in vehicles and is used for dry washing/cleaning substance.	Petrol and diesel are the main causes of air pollution.
These fuels are easily available.	Its reserves are on the verge of finishing.
These fuels are convenient in their use.	Due to increase use of petroleum fuel, CO2 concentration is increasing hence global warming is increasing

Question 3.
The use of petrol, diesel and kerosene is rising day by day. Their smoke is mixing with air and causing air polution. Write your suggestions and views for reducing air pollution.
Answer:
Suggestions to control pollution due to use of petroleum:

1. Petroleum should be used economically and judiciously.
2. Drive vehicles at a constant and moderate speed as far as possible.
3. Switch off the engine at traffic lights or at a place where you have to wait.
4. Ensure correct pressure in tyres.
5. Ensure regular maintenance of the vehicle.
6. Sustainable use of petroleum products is a must so that future generations may also use them.
7. Use unleaded petrol, CNG, LPG to minimise pollution.

Question 4.
List the fuels used in daily life.
Answer:
Wood coal, Hard coal, Dung cakes, Agricultural wastes. Kerosene, diesel, petrol, gasoline, alcohol. Gobar gas, water gas (H₂ + CO) Producer gas (N₂ + CO), Natural gas, Liquefied petroleum gas (LPG) etc. are the fuel used in daily life.

Question 5.
Draw the diagram of extraction of petrol and label it.
Answer:

Question 6. .
Differentiate between complete and incomplete combustion. Explain with example.
Answer:
Complete combustion: When sufficient amount of oxygen is supplied to a burning substance, then it bums with blue flame, it is called complete combustion.
Example: combustion of LPG (liquefied Petroleum Gas).
Incomplete combustion: When any combustion substance do not get sufficient amount of oxygen supply, then it bums with yellow flame. It is called incomplete combustion.
Example: Burning of wood that causes air pollution.

Carbon and Fuel Additional Questions Solved

I. Multiple Choice Questions

Question 1.
Which one of the following is petrochemical?
(a) Ammonia
(b) Coke
(c) Acetone
(d) Paraffin Wax

Question 2.
The fossil fuels are
(a) Inexhaustible
(b) Exhaustible
(c) Petroleum
(d) Laboratory made

Question 3.
Petroleum is found under the
(a) Sedimentary rocks
(b) Water
(c) Sand
(d) Coke

Question 4.
Main constituent of LPG is
(a) Methane
(b) Butane
(c) Ethane
(d) Propane

Question 5 .
The purest form of carbon is
(a) Coal gas
(b) Coal tar
(c) Coke
(d) Petroleum

Question 6.
The natural solid fuel is
(a) Coke
(b) Coal
(c) Coal tar
(d) Coal ga

Question 7.
The petroleum product which is used for road surfacing is
(a) Bitumen
(b) Coal gas
(c) Coke
(d) Coal

Question 8.
What is the leading source of energy used in the United States today?
(a) Coal
(b) Oil resources
(c) Natural gas
(d) Nuclear power

Question 9.
Dead organisms are transformed into petroleum and natural gas in
(a) Absence of air
(b) Presence of air
(c) Presence of sunlight
(d) None of these

Question 10.
Which of these is used as a solvent for dry cleaning
(a) Diesel
(b) Kerosene
(c) Petrol
(d) Paraffin wax

Answers:
1. (d)
2. (b)
3. (a)
4. (b)
5. (c)
6. (b)
7. (a)
8. (a)
9. (a)
10. (c)

Carbon and Fuel Very Short Answer Type Questions

Question 1.
Explain why fossil fuels are exhaustible natural resources?
Answer:
Fossil fuels are limited in nature, and are liable to be exhausted by different human activities. So they are called as exhaustible natural resources.

Question 2.
Define calorific value.
Answer:
The amount of heat given out by a unit mass of a fuel on complete combustion is called calorific value.

Question 3.
What is meant by carbonisation?
Answer:
The slow process of conversion of dead vegetation into coal is called as carbonisation.

Question 4.
Name the useful products obtained from coal.
Answer:
Coal can be subjected to destructive distillation to obtain useful products like coke, coal tar and coal gas.

Question 5.
Name the different places in India, where natural gas has been formed?
Answer:
In our country, natural gas has been formed in Tripura, Jaisalmer and in the offshore of Mumbai and in the Krishna-Godavari delta.

Carbon and Fuel Short Answer Type Questions

Question 1.
What is meant by inexhaustible and exhaustible natural resources?
Answer:
The inexhaustible natural resources are in unlimited quantity and are not likely to be exhausted by different human activities. For example, sunlight, air etc. The exhaustible natural resources are limited in nature and can be exhausted by the different human activities. For example; coal, petroleum and minerals etc.

Question 2.
What is destructive distillation?
Answer:
The process by which organic substances like wood, coal and oil are broken down by heat in the absence of air is known as destructive distillation.

Question 3.
What is coke? What are its uses?
Answer:
Coke is a tough, porous and black substance. It is almost pure form of carbon. Coke is used in the manufacture of steel and in the extraction of many metals.

Question 4.
Define combustion. List the substance undergoing complete and incomplete combustion.
Answer:
A chemical reaction that occurs when oxygen combines with other substances to produce heat and usually light is called combustion. For combustion of any substance the following three things are necessary:

1. Oxygen
2. Particular or optimum temperature.
3. Fuel

Question 5.
Explain the allotropes of carbon.
Answer:
Carbon is found in different forms in nature which are divided into the following two parts:

1. Crystalline form:
   (a) Diamond
   (b) Graphite
2. Amorphous form:
   (a) wood charcoal
   (b) Animal charcoal(Bone charcoal).
   (c) Coke
   (d) kajal (Lamp black).
   (e) Gas carbon.

Question 6.
How is coal formed?
Answer:
Coal is formed by the slow decomposition of forest woods that got buried under the earth’s crust due to natural calamities. Heat and pressure over millions of years changed these plants to coal.

Question 7.
What is natural gas? Write some of its uses?
Answer:
Natural gas is a fossil fuel. It is easy to transport. It is stored under high pressure as compressed natural gas (CNG). It is used in vehicles as fuel. It is compressed and fills in cylinders.

Carbon and Fuel Long Answer Type Questions

Question 1.
What are the different constituents of petroleum? What are the uses of petroleum products?
Answer:
The different constituents of petroleum are:
(a) LPG
(b) Petrol
(c) Kerosene
(d) Diesel
(e) Lubricating oil
(f) Paraffin wax
The different uses of petroleum products are:
(a) Petrol is used as motor fuel, aviation fuel and solvent for dry cleaning.
(b) Kerosene is used as fuel for stoves, lamp and jet aircrafts.
(c) Diesel is used as fuel for heavy motor vehicles, electric generators etc.
(d) Paraffin wax is used as ointment, candles and vaseline.

Question 2.
Define the constituents of crude oil.
Answer:
Crude oil consists of many useful fractions which can be obtained by subjecting it to the process of fractional distillation. These include petroleum gas, gasoline, kerosene, diesel, lubricating oils, paraffin wax and asphalt.

Question 3.
What is PCRA? What are its advices?
Answer:
Petroleum Conservation Research Association (PCRA) is an association involved in conservation of petroleum and the efficient utilization of fuel for both economical as well as environmental purposes.
The advices to save fuel by PCRA are:

1. Drive at a constant and moderate speed as far as possible.
2. Switch off the engine at traffic light or at a place where you have to wait.
3. Ensure current tyre pressure.
4. Ensure regular maintenance of the vehicle