NEW BHARATH MATRICULATION HIGHER SECONDARY ...

NEW BHARATH MATRICULATION HIGHER SECONDARY SCHOOL,TVRNEW BHARATH MATRICULATION HIGHER SECONDARY SCHOOL,TVRNEW BHARATH MATRICULATION HIGHER SECONDARY SCHOOL,TVRNEW BHARATH MATRICULATION HIGHER SECONDARY SCHOOL,TVR

6 STD SCIENCE TERM 3 KEY ANSWER

UNIT 1 Magnetism

I. Choose the appropriate answer:

1.An object that is attracted by magnet.

Answer: (b) plain pins

2.People who made mariner’s compass for the first time.

Answer: c. Chinese

3.A freely suspended magnet always comes to rest in the

Answer: (d) North-South

4.Magnets lose their properties when they are

Answer: c. hit with a hammer

5.Mariner’s compass is used to find the

Answer: (c) direction

II. Fill in the blanks:

1. Artificial magnets are made in different shapes such as Bar-magnet, Horseshoe

magnet , and Ring magnet

2. The materials which are attracted towards the magnet are called magnetic

substances.

3. Paper is not a magnetic material.

4. In olden days, sailors used to find direction by suspending a piece of lodestone

5. A magnet always has two poles.

III. True or False. If False, give the correct statement:

1. A cylindrical magnet has only one pole.

Answer: False. A cylindrical magnet has two poles.

2. Similar poles of a magnet repel each other.

Answer: True.

3.Maximum iron filings stick in the middle of a bar magnet when it is brought near them.

Answer: False. Maximum iron filings stick in the poles of a bar magnet when it is brought

near them.

4. A compass can be used to find East-West direction at any place.

Answer: True . A magnetic compass always points towards the North-South direction.

If the North-South direction is known, then the East-West direction can also be

determined. This direction is perpendicular to the North-South direction, ie.,

perpendicular to the compass needle in the same plane.

5. Rubber is a magnetic material.

Answer: False. Rubber is anon-magnetic material.

IV. Match the following

1. Compass – Magnetic needle

2. Attraction – Opposite poles

3. Repulsion – Like poles

4. Magnetic poles – Maximum magnetic strength

V. Circle the odd ones and give reasons:

1. Iron nail, pins, rubber tube, needle.

Answer: Rubber tube is a non-magnetic substance, others are magnetic substances.

2. Lift, escalator, electromagnetic train, electric bulb.

Answer: Electric bulb does not have magnets others have electromagnets.

3. Attraction, repulsion, pointing direction, illumination.

Answer: Illumination is not a property of magnet, others are magnetic properties.

VI. The following diagrams show two magnets near one another. Use the

words, ‘Attract, Repel, Turn around’ to describe what happens in each case.

Answer:

a. Unlike poles attract one another.

b. Like poles repel each other.

c. Unlike poles attract one another.

d. Perpendicular poles turn around and attract one another.

e. Like poles repel each other.

f. Perpendicular poles turn around and attract one another.

VII. Write down the names of substances :

Answer:

VIII. Give Short Answer:

1. Explain the attraction and repulsion between magnetic poles.

Like poles (N – N, S – S) repel each other.

Unlike poles (N – S, S – N) attract each other.

2. A student who checked some magnets in the school laboratory found out that their

magnetic force is worn out. Give three reasons for that?

Magnets lose their properties if they are:

heated

dropped from a height

hit with a hammer

These are the reasons for that their magnetic force is worn out.

IX. Answer in detail:

1. You are provided with an iron needle. How will you magnetize it?

Place the iron needle on the table.

Take a bar magnet and place one of its poles near one edge of the iron needle.

Rub from one end to another without changing the direction of the pole of the magnet.

Repeat the process for 30 to 40 times. The needle will be magnetized.

If it will not attract pin or iron fillings continue the same process for some more time.

2. How does an electromagnetic train work?

Electromagnets are used in Electromagnetic train.

Electromagnets are magnetised only when current flows through them.

When the direction of current is changed, the poles of the electromagnets are also

changed.

Like poles of the magnets which are attached at the bottom of the train and rai l track

repel each other.

So, the train is lifted from the track up to a height of 10 cm.

We know that we can move any magnetic object with the force of attraction or

repulsion properties of magnets.

This train also moves with the help of the magnets attached on the sides of track and

the magnets fitted at the bottom sideway of the train.

By controlling the current, we can control the magnets and movement of the train.

X. Questions based on Higher Order Thinking Skills:

1. You are provided with iron filings and a bar magnet without labelling the poles of the

magnet. Using this.

How will you identify the poles of the magnet?

Which part of the bar magnet attracts more iron filings? Why?

Answer:

When we place the bar magnet in iron fillings large amount of iron fillings stick on the

two ends of the bar magnet. These ends are poles of the magnet.

Poles will attract more iron filings. Because poles have high magnetic strength.

2. Two bar magnets are given in the figure A and B. By the property of attraction, identify

the North pole and the South pole in the bar magnet (B)

Answer:

The Fig -A has S and N poles.

In the Fig -B magnet, nearer to the North pole of Fig-A is South pole and the next pole is

North pole.

3. Take a glass of water with a few pins inside. How will you take out the pins without

dipping your hands into the water?

Answer:

If we keep a strong bar magnet above the glass of water, all pins inside the water come up

and attract the magnet.

Additional Questions


1._______ made objects are attracted by magnets.

Answer: Iron

2.When N pole of bar magnet is moved closer to the north pole of a magnet it will

Answer: repel

3. Electro magnetic trains can easily attain a speed of _______ km per hour.

Answer: 600

II. Fill up the blanks:

1. The magnetic Ore is called as magnetite

2. Natural magnets do not have a definite shape.

3. Man-made magnets are called Artificial magnets.

4. A compass is an instrument which is used to find directions.

5. Cell phone will also get affected by magnetic field.

lll. Give Short Answer:

1. Give the different shapes of Artificial magnets.

Bar magnet

Horseshoe magnet

Ring magnet

Needle magnet

Oval shape magnet

Disc shape magnet

Cylindrical shape magnet.

2. Differentiate magnetic and non-magnetic substance.

Magnetic substance:

It is attracted by magnets

Ex: Iron, Cobalt, Nickel

Non-magnetic substance:

It is not attracted by magnets

Ex: Paper, Plastic, Glass

3. Define – Poles of a magnet.

The attractive force of the magnet is very large near the two ends. These two ends are

called poles of a magnet.

4. Give the properties of magnets.

Like poles repel each other.

Unlike poles attract each other.

5. What are the objects affected by magnetic field?

Cellphone, Computer and DVD are the objects affected by magnetic field

Unit 2 Water

I. Choose the appropriate answer :

1.Around 97% of water available on earth is _______ water.

Answer: (c) Salty

2. Which of the following is not a part of water cycle?

Answer : (d) Distillation

3. Which of the following processes add water vapour to the atmosphere?

i. Transpiration

ii. Precipitation

iii. Condensation

iv. Evaporation

Answer: (c) i and iv

4. About 30% of the freshwater is found in?

Answer: b. groundwater

5. Using R.O. plant at home eliminates a lot of non-potable water. The best way to

effectively use the expelled water of R.O. plant is _______

Answer: (b) use it for watering plants

II. Fill in the blanks :

1. Only 0.3 percent of natural water is available for human consumption.

2. The process of changing water into its vapour is called Evaporation

3. Dam is built on rivers to regulate water flow and distribute water.

4. Water levels in rivers increase greatly during Raining

5. Water cycle is also called as Hydrological cycle

III. True or False. If False, give the correct statement:

1.Water present in rivers, lakes and ponds is unfit for use by human beings.

Answer: False. Water present in rivers, lakes and ponds is fit for use by human beings.

2. Seas are formed when the water table meets the land surface.

Answer: False. Ponds are formed when the water table meets the land surface.

3. The evaporation of water takes place only in sunlight.

Answer: True.

4. Condensation results in the formation of dew on grass.

Answer: True.

5. Sea water can be used for irrigation as such.

Answer: False. Sea water cannot be used for irrigation as such.

IV. Match the following :

1. Flood - Increased rain fall

2. Surface water - Lake

3, Sunlight - Evaporation

4. Cloud - Water vapour

5. Frozen water - Pole

V. Arrange the following statements in the correct sequence :

1. These vapours condense to form tiny droplets of water.

2. The water droplets come together to form large water droplets.

3. The heat of the sun causes evaporation of water from the surface of the earth,

oceans, lakes, rivers and other water bodies.

4. The large water droplets become heavy and the air cannot hold them, therefore, they

fall as rains.

5. Water vapour is also continuously added to the atmosphere through transpiration

from the surface of the leaves of trees.

6. Warm air carrying clouds rises up.

7. Higher up in the atmosphere, the air is cool.

8. These droplets floating in the air along with the dust particles form clouds.

Answer:

1.The heat of the sun causes evaporation of water from the surface of the earth,

oceans, lakes, rivers and other water bodies.

2.Water vapour is also continuously added to the atmosphere through transpiration

from the surface of the leaves of trees.

3. Higher up in the atmosphere, the air is cool.

4.These vapours condense to form tiny droplets of water.

5. These droplets floating in the air along with the dust particles form clouds.

6. Warm air carrying clouds rises up.

7.The water droplets come together to form large water droplets.

8. The large water droplets become heavy and the air cannot hold them, therefore, they

fall as rains.

VI. Analogy:

1. Population explosion : Water scarcity :: Recycle : Water Management.

2. Ground water :Tube wells :: Surface water : lakes

VII. Give Very Short Answer:

1. Name four different sources of water.

Rivers, wells, lakes, glaciers, ponds etc.

2. How do people in cities and rural areas get water for various purposes?

In city, people get water from water tanks, hand pipes and bore wells.

In rural area, people get water from wells, canals, ponds and rivers.

3. Take out of cooled bottle of water from refrigerator and keep it on a table. After some

time you notice a puddle of water around it. Why?

The cooled surface of bottle cools the air around it and the water vapour of the air

condenses. So after some time a puddle of water can be noticed around the bottle.

4. We could see clouds almost every day. Why doesn’t it rain daily?

The millions of tiny droplets do not collide with another to form larger droplets.

The air around the clouds is not cool.

5. Name the places where water is found as ice.

Polar ice-caps, Ice sheets and glaciers in Artie region arid Antarctica.

6. How do aquatic animals manage to live in Arctic and Antarctic Circle?

In Arctic and Antarctic circle, water in lakes and ponds will be frozen and a solid layer of

ice is formed on the surface of water. Still aquatic animals living under the ice do not die.

This is because the floating layer of ice acts as a protective coat and does not permit heat

to escape from water. So as the surface water alone turns to ice, the aquatic animals

manage it.

7. What are the types of rainwater harvesting?

There are two types of rainwater harvesting.

Collecting water from where it falls.

Collecting rainwater by constructing bunds.


1. Differentiate between surface water and groundwater.

Surface water

Water present on the surface of the earth.

Ex : River, lake, ponds, streams or freshwater.

Groundwater:

Water present beneath earth’s surface in soil.

Ex : open wells, tube wells (or) hand pumps, Spings etc.

2. Write a few slogans of your own on the topic “Save Water”?

“To a thirsty man, a drop of water is worth more than a sack of gold”.

“Water covers 2/3 of the surface of the earth. But only 0.002% is drinkable. Save

water”

“Save water to secure your future”

“Don’t make nature cry, keep your water clean”

“Store water for dry days”.

3. About 71% of earth’s surface is covered with water, then why do we face scarcity of

water?

About 71% of the earth’s surface is covered with water and even then we face scarcity of

water. Reasons:

97% of total water is found in seas and oceans, which is salty and not fit for human

consumption.

Only 3% found is the freshwater and that too available in polar ice caps and glaciers.

Out of 3% fresh water, only 0.3% is available to us as surface water, in lakes, rivers,

and swamps.

4. Give a reason for the following statement – Sewage should not be disposed of in rivers

or oceans before treatment.

Sewage should not be disposed of in rivers or oceans before treatment.

If we dispose of sewage before treatment the rivers and oceans will be polluted.

Aquatic animals and species will die due to pollution.

We can not use the river water for our day to day life.

5. The freshwater available on earth is only 3%. We cannot increase the amount of water.

In that case, how can sustain the water level?

The sewage water treatment is to be adopted.

Decrease the usage of pesticides, insecticides, and fertilizers in agriculture.

Protect forest and trees.

Adopt drip irrigation and sprinkler irrigation in agriculture.

Rainwater harvesting should be implemented in every building.

Create awareness about the impact of throwing wastes into the water bodies.


1. What is potable water? List down its characteristics?

Potable water is the water which is safe to drink.

On average the human body requires 2-3 litres of water per day for proper

functioning.

Characteristics of potable water :

Cleaned of harmful contaminants.

It is transparent.

It is odourless and colourless.

It is harmless or free from disease-causing bacteria.

2. Who is known as Waterman of India? Browse the net and find the details about the

award, the Waterman received for water management. State the findings by drafting a

report.

The ‘Waterman of India’ is Dr. Rajendra Singh. He is a well-known water conservationist

and environmentalist from Alwar district, Rajasthan.

Awards:

He get Ramon Magasaysay award for community leadership in 2001.

In 2005, he got Jamnalal Bajaj award for Science and Technology for rural

development.

In 2008, The Guardian, named him amongst its list of 50 people who could save the

planet.

In 2015, he won Stockholm Water Prize. He runs an NGO called ‘Tarun Bharat

Sangh’ (TBS), which was founded in 1975.

In 2016, he was bestowed with Ahimsa Award by Institute of Jainology based in UK.

3. What is rainwater harvesting? Explain in a few sentences how it can be used in houses.

Direct collection and use of rain water is called rainwater harvesting.

The system is easy to install, operate and maintain for all types of houses.

Excellent and valuable source of water in emergencies.

Reduces rainwater runoff and solve drainage problems in houses.

Ideal solution for inadequacy of water.

Increase groundwater level.

X. Questions based on Higher Order Thinking Skills :

1. When there is no pond or lake in an area, will there be the formation of clouds possible

in that area?

Yes, the formation of clouds is possible at that area because plants also release water

vapour by transpiration process. This water vapour will form clouds.

2. To clean the spectacles, people often breathe out on glasses to make them wet.

Explain why do the glasses become wet.

When we breathe out, the hot air comes out from our mouth which get condensed and

changed into tiny water droplets and glasses become wet.

XI. Crossword :

DOWN:

1. A method of water conservation.

2. Process of getting water vapour from sea water.

6. Water stored in dams is used for generation of _____

ACROSS

3. _______ is a large body of non-potable water found in nature.

4. In summer, the body loses water as _______

5. Plants undergo _______ and contribute to water cycle.

Answer:

Down:

1. Recycling

2. Evaporation

6. Electricity

Across:

3. Ocean

4. Sweat

5. Transpiration

XIl. 1. Observe the given graph carefully and answer the questions.

a. What percentage of water is seen in fish?

b. Name the food item that has maximum amount of water in its content.

c. Name the food item that has minimum amount of water in its content.

d. Human body consists of about _________ percentage of water.

e. Specify the food item that can be consumed by a person when he/she is suffering from

dehydration.

Answer:

a. 70% of water is seen in fish.

b. Watermelon has maximum amount of water in its content.

c. Fish has minimum amount of water in its content.

d. 60%.

e. Watermelon is the food item which can be consumed by a person when he/she is

suffering from dehydration.

2. Look at the map of Tamilnadu showing annual rainfall and answer the questions given

below.

a. Identify the districts that get only low annual rainfall in Tamilnadu.

b. Identify the districts that get a medium annual rainfall in Tamilnadu.

c. State the districts that enjoy high annual rainfall in Tamilnadu.

Answer:

a. Dharmapuri, Erode, Karur, Trichy, Perambalur, Tanjore, Pudukottai, Dindugul,

Madurai, Sivagangai, Ramanathapuram.

b. Thiruvallur, Chennai, Kanchipuram, Vellore, Krishnagiri, Thiruvannamalai, Salem,

Namakkal, Vizhupuram, Ariyalur, Thiruvarur, Thiruppur, Virudunagar, Tuticorin.

c. Cuddalore, Nagappatinam, Nilgiri, Coimbatore, Theni, Thirunelveli, Kanyakumari.



1._______ form of water is present in mountain and polar region.

Answer: (a) Solid

2. The melting point of Ice is ……….

Answer: (b) 0°C

3. _______ water contains 0.05% to 1% of salts.

Answer: (b) Fresh

4. The human body requires ………. litres of water per day for proper functioning.

Answer: (b) 3 – 4 litres

5. In plants, the loss of water in the form of vapour from the aerial parts through _______

Ans: (c) Stomatal Pores

6. _______ water is obtained through open wells, tube wells or hand pumps, springs.

Ans: (d) Ground

7. _______ of Asia’s largest rivers flow from the Himalayas.

Answer: (a) 10

8. Volume of liquid is measured by _______

Answer: (c) Mangrove

9._______ forests are found in pichavaram near Chidambaram

Answer: (c) Mangrov

II. Fill up the blanks:

1. Water plays a vital role in the evolution and survival of life.

2. Vapour is present in the air around us.

3. Every year March 22nd is observed as the world water day.

4. Water level in the reservoirs is measured in Cubic feet per second (cusecs)

lll . Give Short Answer:

1. Give the uses of water.

Cooking food, washing cloths, cleaning utensils, bathing, agricultural etc.

2. What are the three forms of water?

Water is available in solid, liquid and vapour forms.

3. Which places have fresh water?

Ponds, pools, rivers, tube wells have fresh water.

4. Define – Saline water.

Water with a large amount of dissolved solids is not potable or suitable for drinking.

Such water is called saline water.

5. How water is classified based on its salinity?

Based on salinity, water is classified into three main categories. Such as Fresh water,

Brackish water and Sea water.

6. What are the salts dissolved in sea water?

The salts are dissolved in sea water are sodium chloride, magnesium chloride and

calcium chloride.

7. Define – Water cycle.

The water on the earth evaporates into the atmosphere due to the heat of the sun. The

water vapour in the atmosphere forms clouds. From the clouds, water falls on the earth in

the form of rain or snow. By this natural process, water gets renewed. This is called water

cycle.

8. What is transpiration?

It is the process of loss of water from the aerial parts of a plant in vapour form. This is

called transpriation.

IV. Answer in detail:

1. What are the methods of water conservation? Explain?

i. Water management :

Bringing awareness to the people.

Recycling water by separating pollutants.

Minimize the use of fertilizers.

Controlling deforestation.

Adopt drip and sprinkler irrigation in agriculture.

ii. Rainwater harvesting:

Collecting water from where it falls:

Collecting water from the roof tops.

Collecting flowing rain water :

Collecting rain water by constructing dams.

2. Give the importance of water.

The importance of water:

Our body uses water in all its cells, organs and tissues to help regulate its

temperature and maintain other bodily functions.

On an average, the human body requires 2-3 litres of water per day for proper

functioning.

Water helps in digestion of food and removal of toxins from the body.

Water is used in the domestic activities like cooking, bathing, washing clothes,

washing utensils, keeping houses and common places clean, watering plants, etc.

It is also essential for the healthy growth of farm crops and farm stock and is used in

the manufacture of many products.

Industry depends on water at all levels of production.

Unit 3 Chemistry in Everyday Life


1. Soaps were originally made from _______

Answer: (b) animal fats and vegetable oils

2. The saponification of a fat or oil is done using ……….. solution for hot process.

Answer: b. sodium hydroxide

3. Gypsum is added to the cement for _______

Answer: (b) delayed setting

4. Phenol is ……..

Answer: a. carbolic acid

5.Natural adhesives are made from _______

Answer: (c) starch


1. Propanethial s-oxide gas causes tears in our eyes, while cutting onions.

2. Water, coconut oil and animal fat are necessary for soap preparation.

3. Earthworm is called as farmer’s best friend.

4. Organic fertilizer is ecoffiendly.

5.Starch dissolved in water is an example for natural adhesive.

III. True or False. If False, give the correct statement :

1. Concentrated phenol is used as a disinfectant.

Answer: False. Low concentrated phenol is used as a disinfectant.

2. Gypsum is largely used in medical industries.

Answer: False. Gypsum is largely used in cement preparation.

3. Plaster of Paris is obtained from heating gypsum.

Answer: True.

4. Adhesives are the substances used to separate the components.

Answer: False. Adhesives are the substances used to join the components.

5. NPK are the primary nutrients for plants.

Answer: True.


V. Arrange the following statements in correct sequence :

1. Pour that solution into an empty match box, soap can be obtained after drying.

2. Take necessary quantity of water in ajar.

3. Then add coconut oil drop by drop and stir it well.

4. Add concentrated sodium hydroxide in the jar and allow it to cool.

5. Try this soap to wash your hand kerchief.

6. Cover your work area with old newspaper.

Answers:

1. Cover your work area with old newspaper.

2. Take necessary quantity of water in a jar.

3. Add concentrated sodium hydroxide in the jar and allow it to cool.

4. Then add coconut oil drop by drop and stir it well.

5. Pour that solution into an empty match box, soap can be obtained after drying.

6. Try this soap to wash your hand kerchief.

VI. Analogy :

1. Urea : Inorganic fertilizer;

Vermi compost: Organic fertilizer.

2.Starch dissolved in water : Natural adhesives ;

Cello tape : Artifical adhesives.

VII. Give Very Short Answer:

1. What are the three main constituents of soap?

The three main constituents of soap are Lye (Sodium hydroxide), coconut oil and water.

2. What are the two different types of molecules found in the soap?

Loving water molecules.

Hating water molecules.

3. Give an example of inorganic fertilizer.

The Inorganic fertilizers are Urea, Ammonium sulphate and Super phosphate.

4. Mention any three physical properties of phenol?

Weak acid

High volatile

White crystalline powder.

5. Explain the uses of plaster of paris.

Uses of plaster of pairs :

In making black board chalks.

In surgery for setting fractured bones.

For making casts for statues and toys etc.

In the construction industry.

6. What are the ingredients of the cement?

Limestone

Clay

Gypsum

7. Why gypsum is used in cement production?

Gypsum is added to control the setting of cement.


1. Why earthworm is called a farmer’s friend?

Earthworms take organic wastes as food and produce compost castings. So earthworms

are known as Farmers’ Friends because of the multitude of services they provide to

improve soil health and consequently plant health.

2. Explain the process of manufacturing cement.

The cement is manufactured by crushing of naturally occurring minerals such as lime

stone, clay and gypsum through a milling process.

3. What are uses of Gypsum?

Uses of Gypsum :

It is used as fertilizers.

It is used in the process of making cement.

It is used in the process of making Plaster of Paris.


1. How are detergents manufactured?

Manufacture of Detergents:-

Materials used:

Acid slurry, Soda ash (or) Sodium Carbonate, Trisodium phosphate (TSP), sodium

tripolyphosphate (STPP), Carboxy Methyl Chloride (or) Cellulose, Glauber’s salt, colour

perfume and brightner.

Preparation:

Acid slurry is first neutralised.

Then neutralised Acid Slurry is mixed with Soda ash and kept for one hour for

completion of reaction.

Other ingredients such as Trisodium phosphate (TSP), Sodium tripolyphosphate

(STPP), Carboxy Methyl Chloride (or) Cellulose, Glauber’s salt, colour, perfume,

brightner are then blended to the neutralised Acid Slurry with continuous mixing.

Then the mixture is dried.

Now we get detergent powder.

X. Questions based on Higher Order Thinking Skills

1. Ravi is a farmer; he rears many cattle in his farm. His field has many bio wastes. Advise

Ravi how to change this bio waste to compost by using vermi-composting techniques.

Explain the benefits of vermi castings.

A cement tub is to be constructed to a height of 2’A feet and the breadth 3 feet.

Put the Bio-wastes in the cement tub with 5 cm height.

Add few earthworms with the Bio-waste.

Then add saw dust, or coir waste and husk on the top of Bio-wastes.

Then add sand to form a layer of 3 cm.

Then add garden waste on the layer of sand.

Then spray with water.

All layers must be moistioned with water.

After 10 to 15 days, we get vermicompost manure.

Benefits:

It is rich in all essential nutrients.

It improves soil structure, texture and prevent soil corrosion.

It contains valuable hormones like auxons, gibberellin etc.

It neutralizes the soil protection.



1. _______ change results in the change of the substance.

Answer: (b) Chemical

2. The percentage composition of Nitrogen in Ureas is ………..

Answer: (d) 46%

3. _______ is the important material in construction industry.

Answer : (c) cement

4. Who invented cement?

Answer: (b) Joseph Aspdin

5. _______ concrete is a composite material by mixing iron mesh with cement.

Answer: (c) Reinforced cement

6. The molecular formula of ‘Plaster of Paris’ is

Answer: (a) CaSO4. ½ H2O

7. The chemical name of gypsum is .

Answer: (d) Calcium sulphate dihydrate

8. ----is used in making blackboard chalks.

Answer: (a) Plaster of Paris


1. Sodium Chloride – NaCl

2. Calcium sulphate dihydrate – CaSO4.2H2O

3. Magnesium sulphate hydrate – MgSO4.H2O

4. Calcium sulphate hemihydrate – CaSO41/2H2O

5. Phenol – C2H5Oh

V. Analogy:

1. H2O : Water :: NaCl: Sodium Chloride.

2. Used to join components : Adhesives :: Clean the body Soaps.

3. Organic fertilizer : Compost:: Inorganic fertilizer Super phosphate.

4. Used as fertilizer : Gypsum :: Helps nerves function properly : Epsom.

5. Making casts for statues : Plaster of paris :: Used as mouthwash : phenol.

VI. Give Short Answer :

1. Define physical change.

In physical change only the shape, size (or) volume changes; the state of the matter may

also change.

2. What is the use of indicator?

The use of indicator is to identify whether material is acid (or) base medium.

3. How to prepare soft idly?

We could prepare soft idly as a result of chemical change named fermentation takes

place in the idly batter. During fermentation the idly batter undergoes a chemical change

by bacteria.

4. If we soak onion in water the irritation is reduced. Why?

It is due to the presence of a chemical, propanethial s-oxide in onion. This is easily

volatile. When we cut onion, some of the cells are damaged and the chemical come out. It

becomes vapour and reach our eyes result in irritation and tears in eyes. If we soak onion

in water, the chemical is diluted and it cannot reach our eyes. So the irritation is reduced.

5.Write some materials prepared by chemical changes.

Soaps, fertilizers, cement, gypsum, epsom, plaster of paris, phenol are the materials.

6. Define Principal nutrients.

Nitrogen (N), Phosphorous (P) and Potassium (K) are the three important nutrients

among the various nutrients needed for plant growth. These three are called as Principal

Nutrients.

7. Differentiate between organic and inorganic fertilizer.

Organic fertilizers:

Plant (or) animal based materials synthesized by micro-organisms

Prepared easily.

Economical

Example : Vermicompost, Compost

Inorganic fertilizers:

Natural elements by making them undergo chemical changes.

Prepared complicated

Not economical

Example : Urea, Super phosphate, Ammonium Phosphate.

8. Why the cement is called as Portland cement?

It was named Portland cement because it resembled the high quality building stones

found in Portland, England.

9. What are the uses of cement?

It is used to construct houses.

It is used to construct dams, bridges.

10. What is the use of Epsom Salt?

In medical, it eases the stress and relaxes the body.

In agriculture, it improves plant growth.

It is used as medicine for skin problems.

Helps muscles and nerves function properly.

11. Define Adhesives.

A paste like material which is used to join two components together is called adhesive.

VII. Answer in detail :

1. How soaps clean clothes?

We are using wash powder to remove strong stains on the clothes.

The detergent molecules have two sides, one side “water-loving”, other

“water-hating”.

Water hating goes and joins with dirt and oil in the cloth while the water-loving joins

with the water molecules.

When you agitate the cloth the dirt is surrounded by many molecules and is taken

away from the cloth.

The cloth becomes clean, and the dirt surrounded by the detergent molecules float in

the water making it dirty.

Unit 4 Our Environment


1. Identify the fresh water ecosystem.

Answer: (d) All of them

2. Producers are

Answer: c. Plants

3. It is a biodegradable waste

Answer: (b) Coconut shell

4. It is an undesirable change that occurs in air and water.

Answer: c. Pollution

5. Usages of chemical pesticides and fertilisers causes pollution.

Answer: (b) Water pollution


1. Primary consumers that eat plants are called Herbivores

2. Temperature, light and wind are Physical factors.

3. Recycling is the process of converting waste materials into new materials.

4. Water pollution can spread Diseases and chemicals.

5. The 3R’s are Reduce, Reuse and Recycle.

III. True or False. If False, give the correct statement :

1. The Pacific ocean is an example of an aquatic ecosystem.

Answer: True.

2. Bacteria and fungi are called decomposers.

Answer: True.

3. Human and animal wastes are examples of non-biodegradable waste.

Answer: False. Human and animal wastes are examples of biodegradable waste.

4. Excessive use of pesticides leads to air pollution.

Answer: False. Excessive use of pestides leads to water pollution.

5.In schools, waste management rules say that we should separate waste in two

categories.

Answer: True


1. Biotic factor – Animals

2. Sewage – Water pollution

3. Fertilizers – Land pollution

4. Desert – Terrestrial ecosystem

5. Smoke – Air pollution

V. Arrange the following in a correct sequence and form a food chain

1. Rabbit → Carrot → Eagle → Snake

Carrot → Rabbit → Snake → Eagle

2. Human → Insect → Algae → Fish

Algae → Insect → Fish → Human

VI. Give Very Short Answer:

1. Define ecosystem.

An ecosystem is a community of living or biotic and non-living or a biotic things that work

together.

2. What are the two types of ecosystems?

Types of ecosystems :

Natural ecosystem

Artificial ecosystem

3. Write any two things that can be recycled.

Examples :

Old clothes

Plastics

4. What are the types of pollution?

There are four major kinds of pollution :

Air Pollution.

Water Pollution.

Land (Soil) Pollution.

Noise Pollution.

5. Give one example of a food chain in an aquatic ecosystem.

Food chain in aquatic ecosystem.

Aquatic plant → Aquatic insect → Larva → Fish.

6. Name some pollutants.

Toxic gases and fine particles from burning fossil fuels, chemicals released from

factories.

Sewage, industrial effluents, pesticides and fertilizers

Plastics and electronics are land pollutants.

7. What are the pollutions caused by the objects given below?

a. Loud Speaker

b. Plastic

Answer:

a. Loud Speaker – Noise Pollution.

b. Plastic – Land Pollution.

VII. Give Short Answer:

1. What is biodegradable waste?

The term ‘‘Biodegradable” is used for those things that can be easily decomposed by

natural agents like water, oxygen, ultraviolet rays of sun and microorganisms etc.

2. How can we reduce water pollution?

Do not pour leftover oil, old medicines or waste down the drain or into the toilet.

Reduce the use of chemical pesticides and fertilizers to grow crops.

Reduce the use of detergents and bleach to wash clothes.

Do not litter or dump waste always use a waste bin.

3. Write the importance of the food chain.

Importance of food chain

Learning food chain help us to understand the feeding relationship and interaction

between organisms in any ecosystem.

Understanding the food chain also helps us to appreciate the energy flow and nutrient

circulation in an ecosystem.

This is important because pollution impacts the ecosystem. The food chain can be

used to understand the movement of toxic substances and their impacts.

VIII. Answer in detail:

1. Give two examples of how you can avoid or reduce waste?

Examples of how we can Avoid waste:-

Avoid buying packaged foods. Refuse to buy ‘use-and-throw’ plastic products.

Examples of how we can Reduce waste:-

Write on both sides on paper

Share newspaper and magazines with others.

2.Write a short note on noise pollution.

Noise pollution is caused by loud sounds.

Loud music, the sounds of motor vehicles, fireworks and machines cause noise

pollution which affects the environment.

We all like a quiet and peaceful place since unpleasant or loud sounds disturb us.

Continuous noise disturbs our sleep and does not let us study.

It leads to stress and health impacts such as high blood pressure and hearing loss.

Loud noise or music can damage our ears.

It also disturbs animals. For example in noisy areas birds have to communicate

louder so they can hear each other.

Even underwater noise pollution from ships can make whales lose their way as they

use sounds to navigate.

IX. Questions based on Higher Order Thinking Skills

1.What would happen if an organism is removed from the food chain?

If an organism is removed from the food chain,

The food chain will fall apart.

The ecosystem will become imbalance and collapse.

For example, Consider a food chain: Plants → grasshoppers → frogs → snakes →

hawks.

If frogs were to die off in this chain, (due to disease/pollutants), then, there will be an

increase in the number of grasshoppers. This will cause a major problem.

2. Explain the link between waste and dangerous diseases like dengue and malaria?

Dengue and malaria fever are caused by the bite of mosquitoes.

Accumulation of waste and stagnant water or uncovered containers of stored drinking

water are the habitat for breeding mosquitoes.

In order to control these infectious diseases, people should maintain clean

environment, free from mosquitoes.

X. See the diagram and answer the following questions :

1.Explain what is happening in the picture?

The atmosphere is polluted in this picture. It is due to the smoke arising from burning

garbage.

Land and water have been polluted because of leaching the toxins into the soil and

water.

2.What types of pollution are caused by open dumps?

The following types of pollution are caused by open dumps :-

Water pollution

Land pollution

Air pollution

Unit 5 Plants in Daily Life

I. Choose the correct answer :

1. One of the following birds is an example of plant pollinator

Answer: (c) Humming bird

2. Natural Mosquito repellant is

Answer: d. Neem

3. Which of the following is not a root?

Answer: (a) Potato

4. Which of the following medicinal plants has anticancer properties?

Answer: (a) Amla

5. Which is the national tree of India?

Answer: (c) Banyan tree


1. In every year October Sixteenth is celebrated as world food day.

2. Cotton is an example of textile fibre.

3. I am the state tree of Tamilnadu. Who am I Palm tree ?

4. The juice of the leaves of Tulasi plant relieves cough and bronchitis.

5. The edible seeds of leguminous plants are called Pulses

III. True or False – If False, give the correct answer :

1. Plants grown for decorative purposes are called as softwood.

Answer: False. Plants grown for decorative purposes are called Ornamental plants.

2. Silkworm eats mulberry leaves.

Answer: True.

3. Cauliflower is used for ornamental purpose.

Answer: False. Jasmine is used for ornamental purpose.

4. Cotton cloth is not suitable for summer season.

Answer: False. Cotton cloth is suitable for summer season.

5. Sugarcane is used as bio fuel.

Answer: True.


1. Fibre yielding plant – Hemp

2. Hardwood – Teakwood

3. Neem – Chloramine

4. Clove – Spice

5. Millet – Cereals

V. Analogy :

1. mango : fruit:: maize : cereals.

2. coconut: fibre :: rose : ornamental.

3. Bees: Polinate insect:: earthworms : Natural manure.

VI. Give Very Short Answer:

1. What is food?

Any nutritious substance that people or animals eat or drink or that plants absorb in order

to maintain life and growth is called Food.

2. What are the medicinal plants?

Plants that have ingredients which can be used in drug preparation are known as

medicinal plants. (Eg.) Tulsi, Neem etc.

3. How hardwoods differ from softwoods?

Hardwoods:

Present in angiosperms (flowering plants)

It is used to prepare furniture, decks, flooring and wooden construction.

Example: Teak, Jackfruit.

Softwoods:

Present in gymnosperm (non-flowering plants)

It is used to produce plywood, wooden boxes, medium-density fibreboard (MDF) and

paper making.

Example: Katampu, Pine

4. What is spice?

Spices are the aromatic parts of tropical plant traditionally used to flavour food. Bark,

roots, leaves, flowers or stems of certain plants primarily used for flavouring colouring or

preserving food.

(Eg.) roots – vetiver,

leaves – curry leaves

seeds – fenugreek

flower bud – clove

5. Name any three medicinal plants, which are available in your area?

Neem tree, Tulsi tree, Amla tree are the medicinal plants.

6. What are the uses of timber?

A timer is used in the construction of buildings, making of furniture

It is used in making fibreboard, paper making.

VII. Give Short Answer:

1. What is a symbiotic relationship?

The relationship between animals and plants, benefiting both of them is known as a

symbiotic relationship.

(Eg.) Silkworms – feeding on Mulberry leaves – produce silk fibres.

Honey bee – feed on pollen and honey of plants – Agents of cross-pollination and

form vegetables and fruits along with honey.

2. Write the uses of neem?

Neem leaf is used for leprosy, eye disorders, intestinal worms, stomach upset, skin

ulcer, diseases of heart and blood vessels, fever, diabetes and liver problem.

Neem flowers can be used to treat intestinal worm.

Neem oil is rich in vitamin E and fatty acid. It helps to improve skin elasticity.

3. Name any five plants and their parts that we eat.

Carrot, Beetroot and radish – Taproots

Potato, Ginger, Turmeric – Underground stem

Curry leaves, Coriander leaves – Leaves

Drum stick – Leaves, Unripe fruit and bark.

Paddy, Wheat, Maize and Ragi – Seeds

VIII. Answer in detail :

1. Write short notes on – Timber yielding plants.

The wood needed for the construction of buildings and making of furniture are

obtained from certain plants.

We use wood for these purposes due to their features like durability, stylish finishing

and resistance to temperature changes.

All commercial timbers are classified into two classes as Hardwoods and softwoods

based essentially on their structure.

i. Hardwoods:

Hardwoods are angiosperms (flowering plants), the largest group of land plants.

High-quality furniture, decks, flooring and wooden construction are being made only

using hardwood. Example: Teak, Jackffuit.

ii. Softwoods:

Softwoods come from gymnosperm (non-flowering plants) trees. Certain angiosperms

also yield softwood.

Softwoods have a wide range of applications such as making plywood, wooden boxes,

medium-density Fibreboard (MDF) and paper making.

Example: Katampu, Pine.

2. Comment on the importance of plant-animal interaction.

Animal – Plant interactions :

Animals and birds play an important role in spreading seeds of various plants.

The digestive enzymes in the digestive system of the birds soften the protective layer

of the seeds and make it easier to germinate.

If this natural relationship between animals and plants are affected, it shows its

impact on the economy too.

IX. Questions based on Higher Order Thinking Skills :

1. Desert does not have water. Why? Give the reason?

Most deserts get less than 10 inches of rainfall each year.

The evaporation rate is higher than the rainfall.

In the desert, there is little water available for plants (cactus-like) and other

organisms.

Cactus like plants and animals living in such areas are adapted to save water and to

endure drought.

(Eg.) Cactus Camel etc.

2. Kavitha said, “Palm tree is a tall tree, so it gives hardwood”! Do you agree with her

statement (or) not? Explain Why?

No. I don’t agree with her statement.

Palm tree is technically neither hardwood nor softwood.

It comes from a separate family known as Arecaceae.

It has significantly different cellular structure from either soft or hardwoods

3. Look at the diagram given below and answer the following questions,

a. Soil fertility is increased by bacteria. How?

Answer:

Bacteria like Pseudomonas are used to fix atmospheric nitrogen in the soil for agriculture.

So they increase the soil fertility.

b. Honey bees are essential for the reproduction of the plants. Why?

Answer:

Bees are the best pollinators. Bright colour of flower, smell and honey attract honey

bees.

The bees go from one flower to another they leave the pollen grains from their legs.

It results in cross pollination takes place and the formation of vegetable and fruit. So

honey bees are essential for the reproduction of the plants.



1. For making rope, fibres are obtained from _______ free.

Answer: (c) Coconut

2. The wealth of any country largely depends upon its

Answer: (b) Agricultural development

3. ________ are the best for pollinations.

Answer: (d) Honeybees

4. Carpentry works depend on

Answer: (d) Timber plants

5. We obtain _______ from plants for making tyre, seats etc.

Answer: (b) Rubber

6. Neem coated urea releases _______ gradually and helps the plants.

Answer: (c) Nitrogen

ll . Give Short Answer:

1.Define – Economic botany.

Economic botany is the study of the relationship between people and plants and the uses

of plants in the economy.

2. Name the plant from which we get cordage or rope?

Fibres got from coconut stem, stalk of the compound leaf and husk fibres of the coconut

are the sources from which cordage or rope is processed.

3. Define – Cereals.

Cereals are edible components of grain of cultivated grass.

Example : Rice, Wheat, Bajra, Millet.

4. Why do we consider cotton as cash crop?

Cotton give textile fibres used for making garments or dress materials or fabric.

80% cotton is used in making fabrics or cotton mixed fabrics.

Because of its large scale cultivation, manufacture and industry if is a commercially

very important plant. So known as cash crop.

5. Name some medicinal plants.

The medicinal plants are Phyllanthus, Vallarai, Black nightshade, Tippili, Vetiver,

Thuthuvalai, Neem and Tulsi.

6. What are the specialities of Teak Wood?

Teak is a hardwood, durable and strong.

Teak central wood is deposited with gum, resin oil etc and so strong that it can’t

be destroyed by termites and other insects.

Doors, windows, roof and railway sleeper wood and cots are made out of it.

7. Classify the Fibre yielding parts based on the plant parts.

Plant Fibres include seed hairs – Cotton.

Stem Fibres – Flax, jute.

Leaf Fibres – Agave.

Husk Fibres – Coconut.

8. Name some states in which jute crop is grown.

Jute crop is grown in seven states – West Bengal, Assam, Odisha, Bihar, UttarPradesh,

Tripura and Meghalaya.

9. How pollination takes place by insects?

Bright colured flowers, smell and honey attract insects. As the insects go from one flower

to another they leave the pollen grains from their body. This results in cross pollination.

10. Define – Osteoarthritis.

Osteoarthritis is a joint disease affecting joints and knee in old age and any age people.

Pala spinach is used to cure the disease.

Unit 6 Hardware and Software

I Choose the correct answer :

1.Find out the part that is not found in CPU?

Answer: (d) Mouse

2. Which of the following is correct?

Answer: (a) Free and Open source

3. LINUX is a

Answer: (d) Free and Open-source software

4. Find out Paid and Proprietary software from the given list

Answer: (d) All the above

5._______ is a Operating System

Answer : (a) Android


1. MAC OS - Paid and Proprietary Software

2. Software - Geogebra

3. Hardware - RAM

4. Keyboard - Input device

5. LINUX - Free and open source software

III. Short Answer:

1. What are Hardware and Software?

Hardware:

Hardware is the parts of the computer which we can touch and feel.

Hardware includes input and output devices, Cabinet, Hard disk, Mother Board,

SMPS, CPU, RAM, CD Drive and Graphics card.

Software :

Software are programmed and coded application to process the input information.

The software processes the data by converting the input information into coding or

programmed language.

Touching and feeling is not possible. But, we can see the functions of the software in

the form of output.

2. What do you mean by Operating System? How does it work?

System Software (Operating System) is software that makes the hardware devices

process the data inputted by the user and to display the result on the output devices like

Monitor.

Without the operating system, computer cannot function on its own.

Some of the popular operating system are Linux, Windows, Mac, Android etc.

3. What is Free and Open Source Software? Give any two examples?

Free and open software is available at free of cost and can be shared to many

end-users.

Free software is editable and customizable by the user and this leads to update or

development of new software.

Examples: 1. Linux, 2. Geogebra.



1. _____ is a device comprising both hardware and software.

Answer: (d) Computer

2. Which of the following is correct

Answer: (a) Free and Open source software

3. _____ existed before the World Wide Web.

Answer: (b) Email

4. Windows is a

Answer: (a) Paid software

5. _____ is one of the example of application program.

Answer: (a) Drawing tools

6. The license of the software would not be provided unless it is _____

Answer: (b) Purchased

II. Give Short Answer:

1. How can we classify the software?

The software is divided into two types based on the process. They are

System software

Application software

2. Give some examples of System Softwares.

Some of the Popular Operating system are LINUX, Windows, Mac, Android etc.

3. What is open source initiative?

The open source initiative is an organization dedicated to promote open source software.

4. Define – Application Software.

Application software is a program (or) a group of programs designed for the benefit of

end user to work on computer.

The application programs can be installed in the hard disk for the usuage on a

particular computer.

5. What is the classification of System Software?

System software is divided into two types :

System Management Program.

Developing Software.

6. Give the classification of Application Software?

General Purpose Software.

Specific Purpose Software.

7. Give some examples of Specific Purpose Software?

Reservation System.

Attendance System.

Billing System.

Report card Generator.

8. What are the two forms of System and Application Software?

The Operating System and application Software are available in two forms. They are:

Free and Open Source.

Paid and Proprietary Software.

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