Solutions of Coal and Petroleum, Class 8 Chapter 5

 1. What are the advantages of using CNG and LPG as fuels?

Soln:

The advantages of using CNG and LPG as fuels are as follows

• CNG and LPG burn easily.
• CNG and LPG give a lot of heat energy when burnt.
• CNG and LPG can be transported easily through pipelines.
• CNG and LPG are clean fuels and they do not release smoke when burnt.

2. Name the petroleum product used for surfacing of roads.

Soln:

Bitumen is used for surfacing of roads.

3. Describe how coal is formed from dead vegetation. What is this process called?

Soln:

Dense forests got buried under the soil due to natural processes, millions of years ago. More and more soil got deposited over them and they got compressed more. This led them to get exposed to very high temperature and pressure. They slowly got converted into coal under these extreme conditions. The whole process of formation of coal from dead vegetation is known as carbonization.

 4. Fill in the blanks.

(a) Fossil fuels are  ____________,  ____________, and ____________ .

(b) Process of separation of different constituents from petroleum is called _____________ .

(c) Least polluting fuel for a vehicle is ______________ .

Soln:

(a) Fossil fuels Coal, Petroleum, and natural gas.

(b) Process of separation of different constituents from petroleum is called refining.

(c) Least polluting fuel for a vehicle is Compressed Natural Gas (CNG).

5. Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory. (T/F)

(b) CNG is more polluting fuel than petrol. (T/F)

(c) Coke is the almost pure form of carbon. (T/F)

(d) Coal tar is a mixture of various substances. (T/F)

(e) Kerosene is not a fossil fuel. (T/F)

Soln:

a) False

b) False

c) True

d) True

e) False

6. Explain why fossil fuels are exhaustible natural resources.

Soln:

The process of formation of fossil fuels requires millions of years. Dead vegetation and animals that get buried deep inside the earth require high temperature and pressure for the formation of fossil fuels, which cannot be done in the laboratory. Thus, fossils are limited. Therefore, the use of fossil fuels at a rapid rate will lead to their exhaustion.

7. Describe the characteristics and uses of coke.

Soln:

Characteristics:

i) Coke is tough.

ii) Coke is porous.

iii) Coke is black in colour.

Uses:

i) In the manufacture of steel.

ii) In the extraction of metals (as a reducing agent).

8. Explain the process of the formation of petroleum.

Soln:

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.
9. The following table shows the total power shortage in India from 1993–1999. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.

S.No.	Year	Shortage (%)
1.	1993	7.7
2.	1994	7.5
3.	1995	8.2
4.	1996	7.1
5.	1997	7.7
6.	1998	9.1
7.	1999	11.2

Solutions of Separation of Substances, Chapter 5, Class 6

 1. Why do we need to separate different components of a mixture? Give two examples.

Solution:

When two or more substances are mixed together they form a mixture. Components of a mixture should be separated because some components may not be useful or may spoil the useful component of the mixture.

Examples:

Tea leaves are separated from the liquid with a strainer, while preparing tea

Removal of stone pieces from wheat, rice or pulses by hand

2. What is winnowing? Where is it used?

Solution:

The method of separating the components from a mixture is known as winnowing. In this method, heavier and lighter components of a mixture are separated by wind or by blowing air. This method is used by farmers to separate lighter husk particles from heavier seeds of  grain.

3. How will you separate husk or dirt particles from a given sample of pulses before cooking?

Solution:

Husk and dirt particles are separated from pulses by winnowing.

4. What is sieving? Where is it used?

Solution:

Sieving is a method in which fine particles are sieved through holes of the sieve while the bigger impurities remain on the sieve. Sieving is used in a flour mill to separate impurities like husk and stones from wheat before grinding it. It is also used at construction sites to separate pebbles and stones from sand.

5. How will you separate sand and water from their mixture?

Solution:

Sand and water are separated from their mixture by the following steps:

a) The mixture is allowed to stand without any disturbances

b) Now sand settles down

c) Slowly pour the water into another container to obtain sand in the bottom

6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?

Solution:

Yes it is possible to separate sugar mixed with wheat flour by the following method

a) Mix sugar and wheat flour in water

b) Stir the solution to allow sugar to dissolve

c) Now filter the mixture

d) Filtrate contains sugar solution and residue will be wheat flour.

7. How would you obtain clear water from a sample of muddy water?

Solution:

The following process should be carried out to obtain clear water from muddy water

i) Allow muddy water to stand

ii) Mud gets settled down in the water

ii) Slowly pour water to another container

8. Fill up the blanks

(a) The method of separating seeds of paddy from its stalks is called ___________.

(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ___________.

(c) Salt is obtained from seawater by the process of ___________.

(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called ___________.

Solution:

(a) The method of separating seeds of paddy from its stalks is called threshing.

(b) When milk cooled after boiling is poured onto a piece of cloth, the cream (malai) is left behind on it. This process of separating cream from milk is an example of filtration.

(c) Salt is obtained from seawater by the process of evaporation.

(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called decantation.

9. True or false?

(a) A mixture of milk and water can be separated by filtration.

(b) A mixture of powdered salt and sugar can be separated by the process of winnowing

(c) Separation of sugar from tea can be done with filtration.

(d) Grain and husk can be separated with the process of decantation.

Solution:

a) False

b) False

c) False

d) False

10. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?

Solution:

Ice should be added to lemonade after dissolving sugar. It is possible to add more sugar before adding ice.

Sorting Materials into Groups Exercise Questions, CH 4, CLASS 6

 Exercise Questions

1. Name five objects which can be made from wood.

Solution:

a) Table

b) Chair

c) Doors

d) Desk

e) Box

2. Select those objects from the following which shine: Glass bowl, plastic toy, steel spoon, cotton shirt

Solution:

Glass bowl and  steel spoon are the objects which shine

3. Match the objects given below with the materials from which they could be made. Remember, an object could be made from more than one material and a given material could be used for making many objects.

Objects	Material
Book	Glass
Tumbler	wood
Chair	Paper
Toy	Leather
Shoes	Plastics

Solution:

Objects	Material
Book	Paper, Wood
Tumbler	Glass, wood, plastic
Chair	wood, plastic
Toy	Glass, Wood, Paper, Plastics, Leather
Shoes	Leather, Plastic

4. State whether the statements given below are True or False.

(i) Stone is transparent, while glass is opaque.

(ii) A notebook has lustre while eraser does not.

(iii) Chalk dissolves in water.

(iv) A piece of wood floats on water.

(v) Sugar does not dissolve in water.

(vi) Oil mixes with water.

(vii) Sand settles down in water.

(viii) Vinegar dissolves in water.

Solution:

i) False

ii)False

iii) False

iv) True

v) False

vi) False

vii) True

viii) True

5. Given below are the names of some objects and materials:

Water, basket ball, orange, sugar, globe, apple and earthen pitcher. Group them as:

(a) Round shaped and other shapes (b) Eatables and non eatables

Solution:

(a) Round shaped – Basketball, Orange, Globe, Apple, Earthen pitcher

Other shapes – Water, Sugar

(b) Eatables – Water, Orange, Sugar, Apple

Non eatables – Basketball, Globe, Earthen pitcher

6. List all items known to you that float on water. Check and see if they will float on an oil or kerosene.

Solution:

Few items that float on water are as follows:

1. Sponge’s piece
2. Plastic bottle
3. Paper’s piece
4. Thermocol’s piece
5. Wood
6. Plastic ball
7. Cork

However, these items will  not float on an oil or kerosene

7. Find the odd one out from the following:

a) Chair, Bed, Table, Baby, Cupboard

b) Rose, Jasmine, Boat, Marigold, Lotus

c) Aluminum, Iron, Copper, Silver, Sand

d) Sugar, Salt, Sand, Copper sulphate

Solution:

a) Baby – others are made up of wood

b) Boat – others are flowers

c) Sand – others are metals

d) Sand – others are soluble in water

WORKSHEET 1 (Sorting Materials and Groups, CHAPTER 4, CLASS 6)

 1. An iron nail is kept in each of the following liquids. In which case would it lose its shine and appear dull?

(a) Mustard oil
(b) Soft drink
(c) Coconut oil
(d) Kerosene

2. Pick one material from the following which is completely soluble in water.
(a) Chalk powder
(b) Tea leaves
(c) Glucose
(d) Sawdust

3. You are provided with the following materials
(i) magnifying glass
(ii) mirror
(iii) stainless steel plate
(iv) glass tumbler.
Which of the above materials will you identify as transparent?
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (iii) and (iv)

4. Boojho found a bag containing the following materials.
(i) Mirror
(ii) Paper stained with oil
(iii) Magnet
(iv) Glass spectacles
Help Boojho in finding out the material(s) which is/are opaque.

(a) (i) only

(b) (iv) only

(c) (i) and (iii)

(d) (ii) and (iv)

5. While doing an activity in class, the teacher asked Paheli to handover a translucent material. Which among the following materials will Paheli pick and give her teacher?

(a) Glass tumbler

(b) Mirror

(c) Muslin cloth

(d) Aluminium foil

6. Which pair of substances among the following would float in a tumbler half-filled with water?
(a) Cotton thread, thermocol
(b) Feather, plastic ball
(c) Pin, oil drops
(d) Rubber band, coin

7. Which among the following are commonly used for making a safety pin?
(a) Wood and glass
(b) Plastic and glass
(c) Leather and plastic
(d) Steel and plastic

8. Which of the following materials is not lustrous?

(a) Gold

(b) Silver

(c) Wood

(d) Diamond

9. Which of the following statements is not true?
(a) Materials are grouped for convenience.
(b) Materials are grouped to study their properties.
(c) Materials are grouped for fun.
(d) Materials are grouped according to their uses.

10. Find the odd one out from the following.
(a) Tawa
(b) Spade
(c) Pressure cooker
(d) Eraser

11. Which type of the following materials is used for making the front glass (windscreen) of a car?
(a) Transparent
(b) Translucent
(c) Opaque
(d) All the above

Very Short Answer Questions:

12. lt was Paheli’s birthday. Her grandmother gave her two gifts made of metals, one old dull silver spoon and a pair of lustrous gold earrings. She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?

13. Mixtures of red chilli powder in water, butter in water, petrol in water, and honey in water were given to Radha, Sudha, Sofia and Raveena, respectively. Whose mixture is in solution form?

14. On a bright sunny day, Shikha was playing hide and seek with her brother. She hid herself behind a glass door. Do you think her brother will be able to locate her? If yes, why? If no, why not?

15. Take a small cotton ball and place it in a tumbler/ bowl filled with water. Observe it for at least 10 minutes. Will it float or sink in water and why?

16. Which among the following materials would you identify as soft materials and why? Ice, rubber band, leaf, eraser, pencil, pearl, a piece of a wooden board, cooked rice, pulses and fresh chapati.

17. You are provided with the following materials – turmeric, honey, mustard oil, water, glucose, rice flour, groundnut oil.
Make any three pairs of substances where one substance is soluble in the other and any three pairs of substances where one substance remains insoluble in the other substances.

18. During summer holidays, a group of children collected a lump of salt, green grass, broken glass piece, a small thermocol box, pen, iron nail, glass marbles, hair, naphthalene ball, a piece of sugar candy (mishri) and tried to group them on the basis of properties given in table 4.1 below. Help them in filling the table.

Name of the material	Appearance (Hard/Soft)	Transparency (Transparent/Translucent/Opaque)	Floats/Sinks in water	Soluble/Insoluble in water

19. Arrange the jumbled words to arrive at the appropriate names of materials and also write two uses of each.
(a) milaunuim
(b) tcaslpi
(c) soekrnee
(d) gavnier

20. Match the objects given in column I with the materials given in column II.

Column I	Column II
(a) Surgical instruments	(i) Plastic
(b) Newspaper	(ii) Animal product
(c) Electrical switches	(iii) Steel
(d) Wool	(iv) Plant product

21. Pick five objects from the word box given as Fig. 4.1 which are opaque and would sink in water.

O	S	T	P	L	E
A	T	L	E	E	R
C	O	I	N	A	A
O	N	K	C	F	S
A	E	E	I	W	E
L	L	Y	L	R	R

Long Answer Questions:

22. Chalk, iron nail, wood, aluminium, candle, cotton usually look different from each other. Give some properties by which we can prove that these materials are different.

23. Why do you think oxygen dissolved in water is important for the survival of aquatic animals and plants?

24. Differentiate among opaque, translucent and transparent materials, giving one example of each.

25. Sugar, salt, mustard oil, sand, sawdust, honey, chalk powder, petals of a flower, soil, copper sulphate crystals, glucose, wheat flour are some substances given to Paheli. She wants to know whether these substances are soluble in water or not. Help her in identifying soluble and insoluble substances in water.
Solution:

Soluble in water:

Sugar

Salt

Honey

Copper sulphate crystals

Glucose

Insoluble in water:

Mustard oil

Sand

Sawdust

Chalk powder

Petals of flower

Soil

Wheat flour

SOLUTIONS OF WORKSHEET 1 (Sorting Materials and Groups, CHAPTER 4, CLASS 6)

 1. Solution:

(b): Soft drink

Soft drinks contain water, carbon dioxide and acid due to which iron nail is corroded and appears dull.

2. Solution:

(c): Glucose

Glucose is one substance which is completely soluble in water.

3. Solution:

(c): Magnifying glass and glass tumbler

Magnifying glass and glass tumbler are transparent materials.

4. Solution:

Solution:

(c): Mirror and Magnet

A mirror is opaque since it is painted on one side.

Magnet is opaque since it is made up of iron metal.

5. (c): Muslin cloth

Muslin cloth is translucent since we can see through it but not clearly.

Glass tumbler is transparent.

Mirror and aluminum foil are opaque.

6. (b): Feather, plastic ball

Feather and plastic ball will float on water since they are lighter than water.

7. (d): Steel and plastic

Steel can be moulded to get sharp points and plastic is used to seal the edges. Hence steel and plastic are used for making safety pins.

8. Solution:

(c): Wood

Wood is not lustrous since it is not a crystalline substance.

9. Solution:

(c): Materials are grouped for fun.

Materials are usually grouped to study their properties and according to their uses in systematic manner. Hence materials are not grouped for fun.

10. Solution:

(d): Eraser

Eraser is made up of rubber while tawa, pressure cooker and spade are made up of metal.

11. Solution:

(a): Transparent

Transparent glass is used for making the front glass of a car so that everything can be seen clearly.

12. Solution:

Paheli could see the difference in the appearance of two metals since silver reacts with some gases like hydrogen sulphide and loses its shine in moist air. Gold is a noble metal which does not react with the gases present in the atmosphere.

13. Solution:

Raveena will get the mixture in solution form. Since honey and water are soluble with each other hence a solution will be formed when honey is mixed with water.

14. Solution:

Yes, Shikha’s brother could locate her since the glass door which she hid is transparent in nature.

15. Solution:

Initially, the cotton ball floats on water since it is lighter. Slowly it absorbs water and becomes heavy and later sinks in water.

16. Solution:

Leaf, rubber band, cooked rice, eraser and fresh chapati are soft materials because they can be scratched or compressed easily.

17. Solution:

Soluble pairs

(i) Honey – water

(ii) Mustard oil – groundnut oil

(iii) Glucose – water

Insoluble pairs

(i) Mustard oil – water

(ii) Turmeric – water

(iii) Rice flour – water

18. Solution:

Name of the material	Appearance (Hard/Soft)	Transparency (Transparent/Translucent/Opaque)	Floats/Sinks in water	Soluble/Insoluble in water
Lump of salt	Hard	Opaque	Sinks	Soluble
Green grass	Soft	Opaque	Floats	Insoluble
Broken glass piece	Hard	Transparent	Sinks	Insoluble
Thermocol box	Soft	Opaque	Floats	Insoluble
Pen	Hard	Opaque	Floats	Insoluble
Iron nail	Hard	Opaque	Sinks	Insoluble
Glass marbles	Hard	Transparent	Sinks	Insoluble
Hair	Hard	Opaque	Floats	Insoluble
Naphthalene ball	Hard	Opaque	Floats	Insoluble
A piece of sugar candy	Hard	Opaque	Sinks	Soluble

19. Solution:

The arranged word are:

(a) Aluminium – It can be used to wrap food in the foil, in making aircraft, etc.

(b) Plastic – It can be used as buckets/pencil box, etc.

(c) Kerosene – It can be used as fuel, solvent, etc.

(d) Vinegar – It can be used as a preservative, food ingredients, etc.

20. Solution:

The correct match is:

Column I	Column II
(a) Surgical instruments	(iii) Steel
(b) Newspaper	(iv) Plant product
(c) Electrical switches	(i) Plastic
(d) Wool	(ii) Animal product

21. Solution:

Objects that are opaque and would sink in water are:

(i) Coin

(ii) Stone

(iii) Key

(iv) Pencil

(v) Eraser

22. Solution:

Few properties by which we can prove that these materials are different:

Chalk – Hard, rough, non-lustrous

Iron nail – Hard, smooth, lustrous

Wood – Hard, rough, non-lustrous

Aluminium – Hard, smooth, lustrous

Candle – Hard, smooth, non-lustrous

Cotton – Soft, smooth, non-lustrous

23. Solution:

Aquatic animals and plants use oxygen which is dissolved in water for breathing and photosynthesis.

24. Solution:

Those substances through which objects cannot be seen are termed as opaque substances. Example: wood, stone.

Those substances through which objects can be seen but not clearly are termed as translucent substances. Example: frosted glass, oiled paper.

Those substances through which objects can be seen clearly are termed as transparent substances. Example: crystal clear water, glass.

25. Solution:

Soluble in water:

Sugar

Salt

Honey

Copper sulphate crystals

Glucose

Insoluble in water:

Mustard oil

Sand

Sawdust

Chalk powder

Petals of flower

Soil

Wheat flour