NCERT Solutions for Class 10th: Ch 4 Carbon and its Compounds Science

In Text Questions

Page No: 61

1. What would be the electron dot structure of carbon dioxide which has the formula CO₂?

Answer

2. What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? (Hint - the eight atoms of sulphur are joined together in the form of a ring.)

Answer

Page No: 68

1. How many structural isomers can you draw for pentane?

Answer

Three structural isomers are possible for pentane.

2. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Answer

The two features of carbon that give rise to a large number of compounds are as follows:
→ Catenation - It is the ability to form bonds with other atoms of carbon.
→ Tetravalency - With the valency of four, carbon is capable of bonding with four other atoms.

3. What will be the formula and electron dot structure of cyclopentane?

Answer

The formula for cyclopentane is C5H10. Its electron dot structure is given below.

Page No: 69

4. Draw the structures for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal
*Are structural isomers possible for bromopentane?

Answer

(ii) There are many structural isomers possible for bromopentane. Among them, the structures of three isomers are given.

5. How would you name the following compounds?

Answer

(i) Bromoethane
(ii) Methanal (formaldehyde)
(iii) Hexyne

Page No: 71

1. Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Answer

CH₃CH₂OH + (Alkaline KMnO₄) → CH₃COOH
Since, in this reaction one oxygen is added to ethanol, hence it is an oxidation reaction.

2. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Answer

2HC ≡ CH + 5O₂ → 4CO₂ + 2H₂O + Heat
When ethyne is burnt in air, it gives a sooty flame. This is due to incomplete combustion caused by limited supply of air. However, if ethyne is burnt with oxygen, it gives a clean flame with temperature 3000°C because of complete combustion. This oxy-acetylene flame is used for welding. It is not possible to attain such a high temperature without mixing oxygen. This is the reason why a mixture of ethyne and air is not used.

Page No: 74

1. How would you distinguish experimentally between an alcohol and a carboxylic acid?

Answer

We can distinguish between an alcohol and a carboxylic acid on the basis of their reaction with carbonates and hydrogen carbonates. Acid reacts with carbonate and hydrogen carbonate to evolve CO₂ gas that turns lime water milky.

Alcohols, on the other hand, do not react with carbonates and hydrogen carbonates.

2. What are oxidising agents?

Answer

Oxidising agents are the substances that gain electrons in redox reaction and whose oxidation number is reduced.

Page No: 76

1. Would you be able to check if water is hard by using a detergent?

Answer

Detergent gives lather with hard and soft water both, while a soap gives lather with soft water only. Thus, it is not possible to check if water is hard; by using a detergent.

2. People use a variety of methods to wash clothes. Usually after adding the soap, they 'beat' the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Answer

A soap molecule has two parts namely hydrophobic and hydrophilic. With the help of these, it attaches to the grease or dirt particle and forms a cluster called micelle. These micelles remain suspended as a colloid. To remove these micelles, it is necessary to agitate clothes.

Page No: 77

Excercise

1. Ethane, with the molecular formula C₂H₆ has
(a) 6 covalent bonds.
(b) 7 covalent bonds.
(c) 8 covalent bonds.
(d) 9 covalent bonds.
► (b) 7 covalent bonds.

2. Butanone is a four-carbon compound with the functional group
(a) carboxylic acid.
(b) aldehyde.
(c) ketone.
(d) alcohol.
► (c) ketone.

3. While cooking, if the bottom of the vessel is getting blackened on the outside, it means that
(a) the food is not cooked completely.
(b) the fuel is not burning completely.
(c) the fuel is wet.
(d) the fuel is burning completely.
► (b) the fuel is not burning completely.

4. Explain the nature of the covalent bond using the bond formation in CH₃Cl.

Answer

The structure of CH₃Cl is given below:

Carbon has four valence electrons. It shares 1 electron each with 3 hydrogen atoms and 1 electron with chlorine. The bond between C and Cl atoms is covalent but due to higher value of electro-negativity of Cl, the C–Cl bond is polar in nature.

5. Draw the electron dot structures for
(a) ethanoic acid.
(b) H₂S.
(c) propanone.
(d) F₂.

Answer

6. What is a homologous series? Explain with an example.

Answer

A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.

For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is C_nH_2n+2.
Methane CH₄ Ethane CH₃CH₃ Propane CH₃CH₂CH₃ Butane CH₃­CH₂CH₂CH₃ It can be noticed that there is a difference of -CH₂ unit between each successive compound.

7. How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?

Answer

Ethanol and Ethanoic acid be differentiated on the basis of their following properties:
→ Ethanol is a liquid at room temperature with a pleasant smell. Ethanoic acid has a melting point of 17°C. Since it is below the room temperature so, it freezes during winter. Moreover, ethanoic acid has a smell like vinegar.
→ Ethanol does not react with metal carbonates while, ethanoic acid reacts with metal carbonates to form salt, water and carbon dioxide. For example,
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + CO₂ + H₂O
→ Ethanol does not react with NaOH while ethanoic acid reacts with NaOH to form sodium ethanoate and water. For example,
CH₃COOH + NaOH → CH₃COONa + H₂O→ Ethanol is oxidized to give ethanoic acid in presence of acidified KMnO₄ while, no reaction takes place with ethanoic acid in presence of acidified KMnO4.

8. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Answer

Soap molecule has two ends. One end is hydrophilic and another end is hydrophobic. When soap is dissolved in water and clothes are put in the soapy solution, soap molecules converge in a typical fashion to make a structure; called micelle. The hydrophobic ends of different molecules surround a particle of grease and make the micelle; which is a spherical structure. In this, the hydrophilic end is outside the sphere and hydrophobic end is towards the centre of the sphere. This is why micelle formation takes place when soap is added to water.

Since ethanol is not as polar as soap, so micelles will not be formed in other solvents such as ethanol.

9. Why are carbon and its compounds used as fuels for most applications?

Answer

Carbon and its compounds give large amount of heat on combustion due to high percentage of carbon and hydrogen. Carbon compounds used as fuel have optimum ignition temperature with high calorific values and are easy to handle. Their combustion can e controlled. Therefore, carbon and its compounds are used as fuels.

10. Explain the formation of scum when hard water is treated with soap.

Answer

Hard water often contains salts of calcium and magnesium. Soap molecules react with the salts of calcium and magnesium and form a precipitate. This precipitate begins floating as an off-white layer over water. This layer is called scum. Soaps lose their cleansing property in hard water because of formation of scum.

11. What change will you observe if you test soap with litmus paper (red and blue)?

Answer

Since soap is basic in nature, it will turn red litmus blue. However, the colour of blue litmus will remain blue.

12. What is hydrogenation? What is its industrial application?

Answer

Hydrogenation is the chemical reaction between hydrogen and other compounds in the presence of catalyst. Hydrogenation is used mainly to reduce saturated hydrocarbons. Hydrogenation is an addition reaction.For Example: When ethene is heated with the catalyst nickel it is reduced to ethane.

Industrial application:

→ >Hydrogenation is used in many industrial applications. For example; in Petrochemical Industry, hydrogenation is used to convert alkenes into alkanes (paraffins) and cycloalkanes.
→ It is also used to prepare vegetable ghee from vegetable oils.

13. Which of the following hydrocarbons undergo addition reactions:
C_2, H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.

Answer

Unsaturated hydrocarbons undergo addition reactions. Being unsaturated hydrocarbons, C₃H₆ and C₂H₂ undergo addition reactions.

14. Give a test that can be used to differentiate chemically between butter and cooking oil.

Answer

Butter contains saturated fats. Therefore, it cannot be hydrogenated. On the other hand, oil has unsaturated fats. That is why it can be hydrogenated to saturated fats (solids).

15. Explain the mechanism of the cleaning action of soaps.

Answer

The dirt present on clothes is organic in nature and insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remain suspended in the water. Hence, the dust particles are easily rinsed away by water.

NCERT Solutions for Class 10th: Ch 3 Metals and Non-metals Science

In Text Questions

Page No: 40

1. Give an example of a metal which
(i) is a liquid at room temperature.

► Mercury

(ii) can be easily cut with a knife.

► Sodium

(iii) is the best conductor of heat.

► Silver

(iv) is a poor conductor of heat.

► Mercury and Lead

2.Explain the meanings of malleable and ductile.

Answer

Malleable:Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable.
Ductile: Substances that can be drawn into thin wires are called ductile. For example, most of the metals are ductile.

Page no: 46

1. Why is sodium kept immersed in kerosene oil?

Answer

Sodium is high reactive element. If it is kept in open it can explosively react with oxygen to catch fire. Hence to prevent accidental damage sodium is immersed in kerosene oil.

2. Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water

Answer

(i) 3Fe (s) + 4H₂O (g) → Fe₃O₄ (aq) + 4H₂ (g)

(ii) Ca (s) + 2H₂O (l) → Ca(OH)₂ (aq) + H₂ (g) + Heat
      2K (s) + 2H₂O (l) → 2KOH (aq) + H₂ (g) + Heat

3. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.

Metal	Iron (II) sulphate	Cooper (II) sulphate	Zinc sulphate	Silver nitrate
A.	No reaction	Displacement
B.	Displacement		No reaction
C.	No reaction	No reaction	No reaction	Displacement
D.	No reaction	No reaction	No reaction	No reaction

Use the Table above to answer the following questions about metals A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of copper (II) sulphate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Answer

(i) B is most reactive metal.
(ii) B will displace copper from copper sulphate.
(iii) Arrangement of metals in the order of decreasing reactivity B>A>C>D.

4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H₂SO₄.

Answer

Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal.

When iron reacts with dilute H₂SO₄, iron (II) sulphate with the evolution of hydrogen gas is formed.Fe (s) + H₂SO₄ (aq) → FeSO₄ (aq) + H₂ (g)

5. What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.

Answer

When zinc is added to iron (II) sulphate then it will displace the iron from iron sulphate solution as shown in the following chemical reaction.Zn (s) + FeSO₄ (aq) → ZnSO₄ (aq) + Fe (s)

Page No: 49

1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na₂O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?

Answer

(i) The representation of elements with valence electrons as dots around the elements is referred to as electron-dot structure for elements.

(ii)

(iii) The ions present in Na₂O are Na⁺ and O^2- ions and in MgO are Mg²⁺ and O^2- ions.

2. Why do ionic compounds have high melting points?

Answer

Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.

Page No: 53

1. Define the following terms.
(i) Mineral (ii) Ore (iii) Gangue

Answer

(i) Mineral: The naturally occurring compounds of elements are known as Mineral.
(ii) Ore: Minerals from which metals can be extracted profitably are known as ores.
(iii) Gangue: The impurities present in the ore such as sand, rocks etc are non as gangue.

2. Name two metals which are found in nature in the free state.

Answer

The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum.

3. What chemical process is used for obtaining a metal from its oxide?

Answer

A metal can be extracted from its oxide by the process of reduction.

Page No: 55

1. Metallic oxides of zinc, magnesium and copper were heated with the following metals.

Metal	Zinc	Magnesium	Copper
Zinc oxide	-	-	-
Magnesium oxide	-	-	-
Copper oxide	-	-	-

In which cases will you find displacement reactions taking place?

Answer

Metal	Zinc	Magnesium	Copper
Zinc oxide	No reaction	Displacement	No reaction
Magnesium oxide	No reaction	No reaction	No reaction
Copper oxide	Displacement	Displacement	No reaction

2. Which metals do not corrode easily?

Answer

Metals which have low reactivity such as silver, gold does not corrode easily.

3. What are alloys?

Answer

An alloy is the homogeneous mixture of two or more metals or metals and non metals. For example brass is an alloy of copper and zinc.

Page No: 56

Excercise

1. Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl₂solution and aluminium metal
(c) FeSO₄solution and silver metal
(d) AgNO₃solution and copper metal.
► (d) AgNO₃solution and copper metal.

2. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) all of the above.
► (c) Applying a coating of zinc

3. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron
► (a) calcium

4. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.

(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.

► (c) zinc is more reactive than tin.

5. You are given a hammer, a battery, a bulb, wires and a switch.

(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Anwer

(a) With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a non-metal. Similarly, we can use the battery, bulb, wires, and a switch to set up a circuit with the sample. If the sample conducts electricity, then it is a metal otherwise a non-metal.

(b) The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reactions are involved in these tests.

6. What are amphoteric oxides? Give two examples of amphoteric oxides.

Answer

Those oxides that behave as both acidic and basic oxides are called amphoteric oxides.
Examples: aluminium oxide (Al₂O₃), zinc oxide (ZnO)

7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Answer

Iron and aluminium will displace hydrogen from dilute acids as they more reactive then hydrogen. Mercury and copper cannot displace hydrogen from dilute acids as they are less reactive than hydrogen.

Page No: 57

8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer

In the electrolytic refining of a metal M:
Anode → Impure metal M
Cathode → Thin strip of pure metal M
Electrolyte → Solution of salt of the metal M

9. Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

(a) What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?

(b) Write a balanced chemical equation for the reaction taking place.

Answer

(a)

(i) There will be no action on dry litmus paper.

(ii) The colour of litmus paper will turn red because sulphur is a non-metal and the oxides of non-metal are acidic in nature.

(b) S (s) + O₂(g) → SO₂ (g)

10. State two ways to prevent the rusting of iron.

Answer

Two ways to prevent the rusting of iron are:
→ Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water proof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.
→ Galvanisation:An iron article is coated with a layer of zinc metal, which prevents the iron to come in contact with oxygen and moisture. Hence, rusting is prevented.

11. What type of oxides are formed when non-metals combine with oxygen?

Answer

When non-metals are combined with oxygen then neutral or acidic oxides are formed. Examples of acidic oxides are NO₂, SO₂ and examples of neutral oxides are NO, CO etc.

12. Give reasons

(a) Platinum, gold and silver are used to make jewellery.

(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

Answer

(a) Platinum, gold, and silver are used to make jewellery because they are very lustrous. Also, they are very less reactive and do not corrode easily.

(b) Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water.Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.

(c) Though aluminium is a highly reactive metal, it is resistant to corrosion. This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide. This oxide layer is very stable and prevents further reaction of aluminium with oxygen. Also, it is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.

(d) Carbonate and sulphide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulphides.

13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.

Answer

Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result, copper vessel loses its shiny brown surface forming a green layer of copper carbonate. The citric acid present in the lemon or tamarind neutralises the basis copper carbonate and dissolves the layer. That is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic lustre.

14. Differentiate between metal and non-metal on the basis of their chemical properties.

Answer

Metal	Non-metal
Metals are electropositive.	Non-metals are electronegative.
Oxides of metal are basic in nature.	Oxides of non-metals are acidic in nature.
Metals displace hydrogen from dilute acids.	They can't replace hydrogen from dilute acids.
Metals form chlorides which are electrovalent or ionic compounds.	Non-metals form chlorides which are covalent compounds.
They react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam.	They do not react with water.

15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Answer

The solution he had used was Aqua regia. Aqua regia is Latin word which means ‘Royal Water’. It is the mixture of concentrated Hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It is capable of dissolving metals like Gold and Platinum. Since the outer layer of the gold bangles is dissolved in aqua regia so their weight was reduced drastically.

16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).

Answer

Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water.3Fe + 4H₂O → Fe₃O₄ + H₂O
That is why copper is used to make hot water tanks, and not steel.

NCERT Solutions Of Ch - Motion Class - 9

In Text Question

Page No: 100

1. An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.

Answer

Yes,an object can have zero displacement even when it has moved through a distance.This happens when final position of the object coincides with its initial position. For example,if a person moves around park and stands on place from where he started then here displacement will be zero.

2. A farmer moves along the boundary of a square field of side 10 m in 40 s. What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds from his initial position?

Answer

Given, Side of the square field= 10m
Therefore, perimeter = 10 m x 4 = 40 m
Farmer moves along the boundary in 40s.
Displacement after 2 m 20 s = 2 x 60 s + 20 s = 140 s =?
Since in 40 s farmer moves 40 m

Therefore, in 1s distance covered by farmer = 40 / 40 m = 1m

Therefore, in 140s distance covered by farmer = 1 × 140 m = 140 mNow, number of rotation to cover 140 along the boundary= Total Distance / Perimeter
= 140 m  / 40 m  = 3.5 round
Thus, after 3.5 round farmer will at point C of the field.

Thus, after 2 min 20 seconds the displacement of farmer will be equal to 14.14 m north east from intial position.

3. Which of the following is true for displacement?

(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.

Answer

None of the statement is true for displacement First statement is false because displacement can be zero. Second statement is also false because displacement is less than or equal to the distance travelled by the object.

Page No: 102

1. Distinguish between speed and velocity.

Answer

Speed	Velocity
Speed is the distance travelled by an object in a given interval of time.	Velocity is the displacement of an object in a given interval of time.
Speed = distance / time	Velocity = displacement / time
Speed is scalar quantity i.e. it has only magnitude.	Velocity is vector quantity i.e. it has both magnitude as well as direction.

2. Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?

Answer

The magnitude of average velocity of an object is equal to its average speed, only when an object is moving in a straight line.

3. What does the odometer of an automobile measure?

Answer

The odometer of an automobile measures the distance covered by an automobile.

4. What does the path of an object look like when it is in uniform motion?

Answer

An object having uniform motion has a straight line path.

5. During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3 × 10⁸ m s⁻¹.

Answer

Speed= 3 × 10⁸ m s⁻¹ Time= 5 min = 5 x 60 = 300 secs.Distance= Speed x Time
Distance= 3 × 10⁸ m s⁻¹ x 300 secs. = 9 x 10¹⁰ m

Page No: 103

1. When will you say a body is in (i) uniform acceleration? (ii) non-uniform acceleration?

Answer

(i) A body is said to be in uniform acceleration if it travels in a straight line and its velocity increases or decreases by equal amounts in equal intervals of time.
(ii) A body is said to be in nonuniform acceleration if the rate of change of its velocity is not constant.

2. A bus decreases its speed from 80 km h⁻¹ to 60 km h⁻¹ in 5 s. Find the acceleration of the bus.

Answer

3. A train starting from a railway station and moving with uniform acceleration attains a speed 40 km h⁻¹ in 10 minutes. Find its acceleration.

Answer

Page No: 107

1. What is the nature of the distance - 'time graphs for uniform and non-uniform motion of an object?
Answer

When the motion is uniform,the distance time graph is a straight line with a slope.

When the motion is non uniform, the distance time graph is not a straight line.It can be any curve.

2. What can you say about the motion of an object whose distance - time graph is a straight line parallel to the time axis?

Answer

If distance time graph is a straight line parallel to the time axis, the body is at rest.

3. What can you say about the motion of an object if its speed - 'time graph is a straight line parallel to the time axis?

Answer

If speed time graph is a straight line parallel to the time axis, the object is moving uniformly.

4. What is the quantity which is measured by the area occupied below the velocity -time graph?

Answer

The area below velocity-time graph gives the distance covered by the object.

Page No: 109

1. A bus starting from rest moves with a uniform acceleration of 0.1 m s⁻² for 2 minutes. Find (a) the speed acquired, (b) the distance travelled.

Answer

Initial speed of the bus, u= 0

Acceleration, a = 0.1 m/s² Time taken, t = 2 minutes = 120 s

(a) v= u + at
v= 0 + 0×1 × 120
v= 12 ms^–1
(b) According to the third equation of motion:
v² - u²= 2as
Where, s is the distance covered by the bus
(12)² - (0)²= 2(0.1) s
s = 720 m

Speed acquired by the bus is 12 m/s.
Distance travelled by the bus is 720 m.

Page No: 110

2. A train is travelling at a speed of 90 km h⁻¹. Brakes are applied so as to produce a uniform acceleration of −0.5 m s⁻². Find how far the train will go before it is brought to rest.

Answer

Initial speed of the train, u= 90 km/h = 25 m/s
Final speed of the train, v = 0 (finally the train comes to rest)
Acceleration = - 0.5 m s^-2 According to third equation of motion:
v²= u²+ 2 as
(0)²= (25)²+ 2 ( - 0.5) s

Where, s is the distance covered by the train

The train will cover a distance of 625 m before it comes to rest.
3. A trolley, while going down an inclined plane, has an acceleration of 2 cm s⁻². What will be its velocity 3 s after the start?

Answer

Initial Velocity of trolley, u= 0 cms^-1 Acceleration, a= 2 cm s^-2 Time, t= 3 s
We know that final velocity, v= u + at = 0 + 2 x 3 cms^-1 Therefore, The velocity of train after 3 seconds = 6 cms^-14. A racing car has a uniform acceleration of 4 m s - '2. What distance will it cover in 10 s after start?

Answer

Initial Velocity of the car, u=0 ms^-1 Acceleration, a= 4 m s^-2 Time, t= 10 s
We know Distance, s= ut + (1/2)at² Therefore, Distance covered by car in 10 second= 0 × 10 + (1/2) × 4 × 102
= 0 + (1/2) × 4× 10 × 10 m
= (1/2)× 400 m
= 200 m

5. A stone is thrown in a vertically upward direction with a velocity of 5 m s⁻¹. If the acceleration of the stone during its motion is 10 m s⁻² in the downward direction, what will be the height attained by the stone and how much time will it take to reach there?

Answer

Given Initial velocity of stone, u=5 m s^-1 Downward of negative Acceleration, a= 10 m s^-2 We know that 2 as= v²- u²

Page No: 112

Excercise

1. An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?
Answer

Diameter of circular track (D) = 200 m
Radius of circular track (r) = 200 / 2=100 m
Time taken by the athlete for one round (t) = 40 s
Distance covered by athlete in one round (s) = 2π r
= 2 x ( 22 / 7 ) x 100
Speed of the athlete (v) = Distance / Time
= (2 x 2200) / (7 x 40)
= 4400 / 7 × 40
Therefore, Distance covered in 140 s = Speed (s) × Time(t)
= 4400 / (7 x 40) x (2 x 60 + 20)
= 4400 / ( 7 x 40) x 140
= 4400 x 140 /7 x 40
= 2200 m

Number of round in 40 s =1 round
Number of round in 140 s =140/40
=3 ¹/₂ After taking start from position X,the athlete will be at postion Y after 3 ¹/₂ rounds as shown in figure

Hence, Displacement of the athlete with respect to initial position at x= xy

= Diameter of circular track
= 200 m

2.  Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph's average speeds and velocities in jogging (a) from A to B and (b) from A to C?

Answer

Total Distance covered from AB = 300 m
Total time taken = 2 x 60 + 30 s
=150 s

Therefore, Average Speed from AB = Total Distance / Total Time
=300 / 150 m s^-1 =2 m s^-1 Therefore, Velocity from AB =Displacement AB / Time = 300 / 150 m s^-1 =2 m s^-1 Total Distance covered from AC =AB + BC
=300 + 200 m

Total time taken from A to C = Time taken for AB + Time taken for BC
= (2 x 60+30)+60 s
= 210 s
Therefore, Average Speed from AC = Total Distance /Total Time
= 400 /210 m s^-1 = 1.904 m s^-1

Displacement (S) from A to C = AB - BC
= 300-100 m
= 200 m

Time (t) taken for displacement from AC = 210 s

Therefore, Velocity from AC = Displacement (s) / Time(t)
= 200 / 210 m s^-1 = 0.952 m s^-1

3. Abdul, while driving to school, computes the average speed for his trip to be 20 km h⁻¹. On his return trip along the same route, there is less traffic and the average speed is 40 km h⁻¹. What is the average speed for Abdul’s trip?

Answer

The distance Abdul commutes while driving from Home to School = S
Let us assume time taken by Abdul to commutes this distance = t₁ Distance Abdul commutes while driving from School to Home = S
Let us assume time taken by Abdul to commutes this distance = t₂ Average speed from home to school v_1av = 20 km h_-1 Average speed from school to home v_2av = 30 km h^-1 Also we know Time taken form Home to School t₁ =S / v_1av Similarly Time taken form School to Home t₂ =S/v_2av Total distance from home to school and backward = 2 S
Total time taken from home to school and backward (T) = S/20+ S/30
Therefore, Average speed (V_av) for covering total distance (2S) = Total Dostance/Total Time
= 2S / (S/20 +S/30)
= 2S / [(30S+20S)/600]
= 1200S / 50S
= 24 kmh^-1
4. A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 m s⁻² for 8.0 s. How far does the boat travel during this time?

Answer

Given Initial velocity of motorboat,  u = 0
Acceleration of motorboat,  a = 3.0 m s^-2 Time under consideration,  t = 8.0 s
We know that Distance, s = ut + (1/2)at² Therefore, The distance travel by motorboat = 0 x 8 + (1/2)3.0 x 8 2
= (1/2) x 3 x 8 x 8 m
= 96 m
5. A driver of a car travelling at 52 km h⁻¹ applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h⁻¹ in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

Answer

As given in the figure below PR and SQ are the Speed-time graph for given two cars with initial speeds 52 kmh-1 and 3 kmh-1 respectively.

Distance Travelled by first car before coming to rest =Area of △ OPR
= (1/2) x OR x OP
= (1/2) x 5 s x 52 kmh-1
= (1/2) x 5 x (52 x 1000) / 3600) m
= (1/2) x 5x (130 / 9) m
= 325 / 9 m
= 36.11 m
Distance Travelled by second car before coming to rest =Area of △ OSQ
= (1/2) x OQ x OS
= (1/2) x 10 s x 3 kmh-1
= (1/2) x 10 x (3 x 1000) / 3600) m
= (1/2) x 10 x (5/6) m
= 5 x (5/6) m
= 25/6 m
= 4.16 m

6. Fig 8.11 shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:

(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?

(c) How far has C travelled when B passes A?
(d)How far has B travelled by the time it passes C?

Answer

(a) Object B
(b) No
(c) 5.714 km
(d) 5.143 km

Therefore, Speed = slope of the graph
Since slope of object B is greater than objects A and C, it is travelling the fastest.

(b) All three objects A, B and C never meet at a single point. Thus, they were never at the same point on road.

On the distance axis:
7 small boxes = 4 km
Therefore,1 small box = 4 / 7 Km
Initially, object C is 4 blocks away from the origin.
Therefore, Initial distance of object C from origin = 16 / 7 Km
Distance of object C from origin when B passes A = 8 km
Distance covered by C

Page No: 113

7. A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m s⁻², with what velocity will it strike the ground? After what time will it strike the ground?

Answer

Let us assume, the final velocity with which ball will strike the ground be 'v' and time it takes to strike the ground be 't'
Initial Velocity of ball,  u =0
Distance or height of fall,  s =20 m
Downward acceleration,  a =10 m s^-2 As we know, 2as =v²-u² v² = 2as+ u² = 2 x 10 x 20 + 0
= 400
∴ Final velocity of ball, v = 20 ms^-1 t = (v-u)/a
∴Time taken by the ball to strike = (20-0)/10
= 20/10
= 2 seconds

8. The speed-time graph for a car is shown is Fig. 8.12.


(a) Find out how far the car travels in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.

(b) Which part of the graph represents uniform motion of the car?

Answer

(a)

The shaded area which is equal to 1 / 2 x 4 x 6 = 12 m represents the distance travelled by the car in the first 4 s.

(b)

The part of the graph in red colour between time 6 s to 10 s represents uniform motion of the car.

10. State which of the following situations are possible and give an example for each of these:
(a) an object with a constant acceleration but with zero velocity.
(b) an object moving in a certain direction with an acceleration in the perpendicular direction.

Answer

(a) Possible
When a ball is thrown up at maximum height, it has zero velocity, although it will have constant acceleration due to gravity, which is equal to 9.8 m/s2.

(b) Possible
When a car is moving in a circular track, its acceleration is perpendicular to its direction.

11. An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth.

Answer

Radius of the circular orbit, r= 42250 km
Time taken to revolve around the earth, t= 24 h
Speed of a circular moving object, v= (2π r)/t
=[2× (22/7)×42250 × 1000] / (24 × 60 × 60)
=(2×22×42250×1000) / (7 ×24 × 60 × 60) m s^-1 =3073.74 m s ^-1

NCERT Solutions Of Diversity In Living Organisms

In Text Questions

Page No: 80

1. Why do we classify organisms?

Answer

There are millions of organisms on this earth. So, it is harder to study them one by one. Therefore, we look for similarities among them and classify them into different classes to study these different classes as a whole. Classification makes our study easier.

2. Give three examples of the range of variations that you see in life-forms around you.

Answer

Examples of range of variations observed in daily life are:
→ Organisms vary greatly in size-from microscopic bacteria to elephants, whales and large trees.
→ The colour of various animals is quite different. Some worms are even colourless or transparent. Various types of pigments are found in plants.
→ The life span of different organisms is also quite varied. For example, a crow lives for only 15 years, whereas a parrot lives for about 140 years.

Page No: 82

1. Which do you think is a more basic characteristic for classifying organisms?
(a) The place where they live.
(b) The kind of cells they are made of. Why?

Answer

The more basic characteristic for classifying organisms is the kind of cells they are made of because different organisms may share same habitat but may have entirely different form and structure. So, the place where they live cannot be a basis of classification.

2. What is the primary characteristic on which the first division of organisms is made?

Answer

The primary characteristic on which the first division of organisms is made is the nature of the cell – prokaryotic or eukaryotic cell.

3. On what basis are plants and animals put into different categories?

Answer

Plants and animals are put into different categories on the basis of Mode of nutrition.Plants are autotrophs. They can make their food own while animas are heterotrophs which are dependent on others for food. Also, locomotion, absence of chloroplasts etc. make them different.

Page No: 83

1. Which organisms are called primitive and how are they different from the so-called advanced organisms?

Answer

A primitive organism is the one which has a simple body structure and ancient body design or features that have not changed much over a period of time.As per the body design, the primitve organisms which hav simple structures are different from those so-called advanced organisms which have complex body structure and organization.

2. Will advanced organisms be the same as complex organisms? Why?

Answer

Yes, because the advanced organisms also were like the primitive ones once. They have acquired their complexity relatively recently. There is a possibility that these advanced or 'younger' organisms acquire more complex structures during evolutionary time to compete and survive in the changing environment.

Page No: 85

1. What is the criterion for classification of organisms as belonging to kingdom Monera or Protista?

Answer

The organisms belonging to Kingdom Monera are unicellular and prokaryotic whereas the organisms belonging to Kingdom Protista are unicellular and eukaryotic.

2. In which kingdom will you place an organism which is single-celled, eukaryotic and photosynthetic?

► Kingdom Protista

3. In the hierarchy of classification, which grouping will have the smallest number of organisms with a maximum of characteristics in common and which will have the largest number of organisms?

Answer

In the hierarchy of classification,a species will have the smallest number of organisms with a maximum of characteristics in common, whereas the kingdom will have the largest number of organisms.

Page No: 88

1. Which division among plants has the simplest organisms?

► Division Thallophyta

2. How are pteridophytes different from the phanerogams?

Answer

Pteridophyta	Phanerogams
They have inconspicuous or less differentiated reproductive organs.	They have well developed reproductive organs.
They produce naked embryos called spores.	They produce seeds.
Ferns, Marsilea, Equisetum, etc. are examples of pteridophyta.	Pinus, Cycas, fir, etc. are examples of phanerogams.

3. How do gymnosperms and angiosperms differ from each other?

Answer

Gymnosperm	Angiosperm
They are non-flowering plants.	They are flowering plants.
Naked seeds not enclosed inside fruits are produced.	Seeds are enclosed inside fruits.
Pinus, Cedar, fir, Cycas, etc. are some examples of gymnosperms.	Coconut, palm, mango, etc. are some examples of angiosperms.

Page No: 94

1. How do poriferan animals differ from coelenterate animals?

Answer

Porifera	Coelenterate
They are mostly marine, non-motile, and found attached to rocks.	They are exclusively marine animals that either live in colonies or have a solitary life-span.
They show cellular level of organisation.	They show tissue level of organisation.
Spongilla, Euplectella, etc. are poriferans.	Hydra, sea anemone, corals, etc. are coelenterates.

2. How do annelid animals differ from arthropods?

Answer

Annelids	Arthropods
The circulatory system of annelids is closed.	Arthropods have an open circulatory system.
The body is divided into several identical segments.	The body is divided into few specialized segments.

3. What are the differences between amphibians and reptiles?

Answer

Amphibian	Reptiles
They have a dual mode of life.	They are completely terrestrial.
Scales are absent.	Skin is covered with scales.
They lay eggs in water.	They lay eggs on land.
It includes frogs, toads, and salamanders.	It includes lizards, snakes, turtles, chameleons, etc.

4. What are the differences between animals belonging to the Aves group and those in the mammalia group?

Answer

Aves	Mammals
Most birds have feathers and they possess a beak.	They do not have feathers and the beak is also absent.
They lay eggs. Hence, they are oviparous.	Some of them lay eggs and some give birth to young ones. Hence, they are both oviparous and viviparous.

Page No: 97

Excercise

1. What are the advantages of classifying organisms?

Answer

Following are the advantages of classifying organisms:
→ It makes us aware of and gives us information regarding the diversity of plants and animals.
→ It makes the study of different kinds of organisms much easier.
→ It tells us about the inter-relationship among the various organisms.
→ It helps us understanding the evolution of organisms.
→ It helps in the development of other life sciences easy.

→ It helps environmentalists to develop new methods of conservation of plants and animals.

2. How would you choose between two characteristics to be used for developing a hierarchy in classification?

Answer

We choose that characteristics which depends on the first characteristics and determines the rest variety.

3. Explain the basis for grouping organisms into five kingdoms.

Answer

The basis for grouping organisms into five kingdoms are:
→ Complexity of cell structure - There are two broad categories of cell structure: Prokaryotic and Eukaryotic. Thus, two broad groups can be formed, one having prokaryotic cell structure and the other having eukaryotic cell structure. Presence or absence of cell wall is another important characteristic.
→ Unicellular and multicellular organisms - This characteristic makes a very basic distinction in the body designs of organisms and helps in their broad categorizations.

→ Cell Wall: Presence and absence of cell wall leads into grouping.

→ Mode of nutrition -Organisms basically have two types of nutritions - autotrophic who can manufacture their own food and heterotrophic who obtain their food from external environment, i.e., from other organisms). Thus, organisms can be broadly classified into different groups on the basis of their mode of nutrition.

4. What are the major divisions in the Plantae? What is the basis for these divisions?

Answer

The major divisions in Kingdom Plantae are:
→Thallophyta
→ Bryophyta
→ Pteridophyta
→ Gymnosperms
→ Angiosperms

The following points constitute the basis of these divisions:
→ Whether the plant body has well differentiated, distinct components.
→ whether the differentiated plant body has special tissues for the transport of water and other substances.
→ The ability to bear seeds.
→ Whether the seeds are enclosed within fruits.

5. How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?

Answer

The characteristics used to classify plants is different from animals because the basic design are different, based on the need to make their own food (plants) or acquire food (animals).
Criteria for deciding divisions in plants are:
→ Differentiated/ Undifferentiated plant body
→ Presence/ absence of vascular tissues
→With/without seeds
→ Naked seeds/ seeds inside fruits

But the animals can't be divided into groups on these criteria. It is because the basic designs of animals are very different from plants. They are divided on the basis of their body structure.

6. Explain how animals in Vertebrata are classified into further subgroups.

Answer

Animals in Vertebrata are classified into five classes:

(i) Class Pisces: This class includes fish such as Scoliodon, tuna, rohu, shark, etc. These animals mostly live in water. Hence, they have special adaptive features such as a streamlined body, presence of a tail for movement, gills, etc. to live in water.

(ii) Class Amphibia: It includes frogs, toads, and salamanders. These animals have a dual mode of life. In the larval stage, the respiratory organs are gills, but in the adult stage, respiration occurs through the lungs or skin. They lay eggs in water.

(iii) Class Reptilia: It includes reptiles such as lizards, snakes, turtles, etc. They usually creep or crawl on land. The body of a reptile is covered with dry and cornified skin to prevent water loss. They lay eggs on land.

(iv) Class Aves: It includes all birds such as sparrow, pigeon, crow, etc. Most of them have feathers. Their forelimbs are modified into wings for flight, while hind limbs are modified for walking and clasping. They lay eggs.

(v) Class Mammalia: It includes a variety of animals which have milk producing glands to nourish their young ones. Some lay eggs and some give birth to young ones. Their skin has hair as well as sweat glands to regulate their body temperature.

NCERT Solutions Of Ch- Tissue Class - 9

In Text Questions

Page No: 69

1. What is a tissue?

Answer

Tissue is a group of cells that are similar in structure and are organised together to perform a specific task.

2. What is the utility of tissues in multi-cellular organisms?

Answer

In multicellular organisms, the different types of tissues perform different functions. Since a particular group of cells carry out only a particular function, they do it very efficiently. So, multicellular organisms possess a definite division of labour.

Page No: 74

1. Name types of simple tissues.

Answer

Simple permanent tissues are of three types:→ Parenchyma
→ Collenchyma

→ Sclerenchyma

Parenchyma tissue is of further two types:

• Aerenchyma

• Chlorenchyma

2. Where is apical meristem found?

Answer

Apical meristem is present at the growing tips of stems and roots.

3. Which tissue makes up the husk of coconut?

Answer

Sclerenchyma tissue makes up the husk of coconut.

4. What are the constituents of phloem?

Answer

The constituents of phloem are:
→ Sieve tubes
→ Companion cells
→ Phloem parenchyma
→ Phloem fibres

Page No: 78

1. Name the tissue responsible for movement in our body.

► Muscular tissue

2. What does a neuron look like?

Answer

Neuron look like a star shaped cell with a tail.

3. Give three features of cardiac muscles.

Answer

Three features of cardiac muscles are:
→ Cardiac muscles are involuntary muscles that contract rapidly, but do not get fatigued.
→ The cells of cardiac muscles are cylindrical, branched, and uninucleate.
→ They control the contraction and relaxation of the heart.

4. What are the functions of areolar tissue?

Answer

Functions of areolar tissue:
→ It helps in supporting internal organs.
→ It helps in repairing the tissues of the skin and muscles.

Page No: 79

Excercise

1. Define the term "tissue".

Answer

Tissue is a group of cells that are similar in structure and are organized together to perform a specific task.

2. How many types of elements together make up the xylem tissue? Name them.

Answer

Xylem is composed of following elements:
→ Tracheids
→ Vessels
→ Xylem parenchyma
→ Xylem fibres

3. How are simple tissues different from complex tissues in plants?

Answer

Simple tissue	Complex tissue
These tissues consist of only one type of cells.	These tissues are made up of more than one type of cells.
The cells are more or less similar in structure and perform similar functions.	Different types of cells perform different functions. For example, in the xylem tissue, tracheids help in water transport, whereas parenchyma stores food.
Three types of simple tissues in plants are parenchyma, collenchyma, and sclerenchyma.	Two types of complex permanent tissues in plants are xylem and phloem.

4. Differentiate between parenchyma, collenchyma and sclerenchyma, on the basis of their cell wall.

Answer

Parenchyma	Collenchyma	Sclerenchyma
Cell walls are relatively thin, and the cells in parenchyma tissues are loosely packed.	The cell wall is irregularly thickened at the corners, and there is very little space between the cells.	The cell walls are uniformly thickened, and there are no intercellular spaces.
The cell wall in this tissue is made up of cellulose.	Pectin and hemicellulose are the major constituents of the cell wall.	An additional layer of the cell wall composed mainly of lignin is found.

5. What are the functions of the stomata?

Answer

The functions of stomata are:
→ The exchange of gases (CO₂ and O₂) with the atmosphere.
→ The loss of excess water in the form of water vapour which is known as transpiration.
6. Diagrammatically show the difference between the three types of muscle fibres.

Answer

The three types of muscle fibres are: Striated muscles, smooth muscles (unstriated muscle fibre), and cardiac muscles.

7. What is the specific function of the cardiac muscle?

Answer

The specific function of the cardiac muscle is to control the contraction and relaxation of the heart.

8. Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.

Answer

Striated muscle	Unstriated muscle	Cardiac muscle
On the basis of structure:
Cells are cylindrical	Cells are long	Cells are cylindrical
Cells are not branched	Cells are not branched	Cells are branched
Cells are multinucleate	Cells are uninucleate	Cells are uninucleate
Alternate light and dark bands are present	There are no bands present	Faint bands are present
Its ends are blunt	Its ends are tapering	Its ends are flat and wavy
On the basis of location:
These muscles are present in body parts such as hands, legs, tongue, etc.	These muscles control the movement of food in the alimentary canal, the contraction and relaxation of blood vessels, etc.	These muscles control the contraction and relaxation of the heart

9. Draw a labelled diagram of a neuron.

Answer

10. Name the following:

(a) Tissue that forms the inner lining of our mouth.
► Epithelial tissue

(b) Tissue that connects muscle to bone in humans.
► Tendon

(c) Tissue that transports food in plants.
► Phloem

(d) Tissue that stores fat in our body.
► Adipose tissue

(e) Connective tissue with a fluid matrix.
► Blood

(f) Tissue present in the brain.

► Nervous tissue

11. Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.

Answer

→ Skin: Stratified squamous epithelial tissue
→ Bark of tree: Simple permanent tissue
→ Bone: Connective tissue
→ Lining of kidney tubule: Cuboidal epithelial tissue
→ Vascular bundle: Complex permanent tissue

12. Name the regions in which parenchyma tissue is present.

Answer

Leaves, fruits, and flowers are the regions where the parenchyma tissue is present.

13. What is the role of epidermis in plants?

Answer

Epidermisis present on the outer surface of the entire plant body which perform following role:
→ It is a protective tissue of the plant body.
→ It protects the plant against mechanical injury.
→ It allows exchange of gases through the stomata.

14. How does the cork act as a protective tissue?

Answer

The outer protective layer or bark of a tree is known as the cork. It is made up of dead cells. Therefore, it protects the plant against mechanical injury, temperature extremes, etc. It also prevents the loss of water by evaporation.

15. Complete the table:

Answer