Force - Class 9 Science

Important Points

Force - Force generally denotes push or pull. Force can :
i. produce motion
ii. stop motion
iii. change the direction of motion
iv. change the dimension in a body
The SI unit of Force is N

Newton's Laws of Motion

Newton's First Law of Motion - A body will continue in its state of rest or uniform motion in a straight line, unless compelled by some unbalance applied force to change its state of rest or uniform motion.

Newton's Second Law of Motion - The rate of change of momentum of a body is directly proportional to the applied unbalanced force and takes place in the same direction in which the force is applied.

Newton's Third Law of Motion - To every action there is an equal and opposite reaction.

Momentum - The force(impact) which a body possesses due to the combined effect of mass and velocity is called momentum. Momentum is denoted by p, where p = m*v where m-mass, v-velocity
The SI unit of momentum is kgms^-1

Mass - Mass is the measure of an object's inertia, more the mass more the inertia. It is a property of material , so it does not change with place.
The SI unit of mass is kg

Law of Conservation of Momentum - In a given system, the sum total of momentum is a constant quantity, provided no external force acts on the body or
In a given system, when two or more bodies interact and no external force acts on them, the total momentum of all bodies is conserved.

Inertia - Mass of a body is the measure of its inertia, i.e., the more the mass of a body, the more is its inertia.

Law of Inertia - The tendency of a body to continue in its state of rest or uniform motion in a straight line, unless some external unbalanced force is applied.

Inertia of rest - The tendency of a body at rest to remain at rest unless acted by an external force is called inertia of rest.

Inertia of motion - The tendency of a body in motion to remain in uniform motion in a straight line unless acted by an external force is called inertia of motion.

---

Questions and Answers

• Give two examples from everyday life where the Newton's third law of motion comes into place.
Ans. Example 1 - Rubber Ball rebounding: When we hit a rubber ball on the ground with some force(action), the ground reacts in opposite direction with an equal force and hence the rubber ball rebounds.
Example 2. Hurting of hand when we hammer a nail on a wodden plank - When we hit a nail with hammer on a wooden plank we apply a force then the nail reacts back with equal force on the hammer. As the hammer is held firmly in our hand, therefore, we feel hurt in our hand.


• Why does a boatman push the river bank backward with a long bamboo pole, on launching his boat in water? Explain.
Ans. It is based on Newton's third law of motion. When the boatman standing in the boat, pushes the river bank backward with a long bamboo pole, the surface of the bank reacts back and pushes the pole in the forward direction. As the pole is in the hands of the boatman, standing in the boat, the whole system moves in the forward direction.


• Why is it difficult to walk on marshy land? Explain.
Ans. It is based on Newton's third law of motion. When we push the marshy soil with our feet the soil yields. Thus, the reaction of the marshy soil is not as much as the action done on it. This makes it difficult to walk on marshy land.


• Why does a boatman push water backward with the oars, while rowing a boat? Explain.
Ans. It is based on Newton's third law of motion. When a boatman pushes water backward with the oars then water also exerts a reaction force which enables the boat to move forward.


• Why does a boatman tie his boat to a pillar, before allowing the passengers to step on the river bank? Explain.
Ans. When the passengers start disembarking, they push the floor of the boat backward with the feet. Now the boat is in water, and the water yields under the impact of this force. Thus, the boat starts sliding backward. To avoid the boat from sliding backward into water, the boatman ties his boat with a rope to a pillar before allowing passengers to disembark.


• Why do the birds flap their wings downward while taking a flight? Explain.
Ans. It is based on Newton's third law of motion. When the birds flap their wings downward they do action on the wind. The wind in turn reacts back and pushes the wings and hence the birds fly in the upward direction.


• Do the action and reaction act on the same body or different bodies? How are the action and reaction related to each other in :
  (a)magnitude and (b)direction? Do they act simultaneously or not?
Ans. Action and reaction act on two different bodies. Action and reaction are equal in magnitude but they act in opposite directions so there is simultaneous action and reaction.


• Why does a gun recoil backward when fired? Explain.
Ans. When the bullet under the impact of exploding gun powder moves out of the barrel from gun with a certain momentum, the gun, in order to conserve momentum, moves with the same momentum (momentum equal to that of bullet) in backward direction. So the net momentum is again zero. Thus, the gun recoils backward.


• Why does an inflated baloon rise up vertically for some distance, when punctured from below? Explain.
Ans. Initially, the balloon and the air in it, are in a state of rest and hence, have zero momentum. However, when the balloon is punctured from below, the air rushes out of it in downward direction with a certain momentum. Thus, in order to conserve momentum the balloon rises up vertically with the same momentum.


• Why do the pieces of cracker fall in all directions when it is burst? Explain.
Ans. When a cracker is not burst the momentum of the cracker is zero. When it is being burst the pieces move in all directions with certain momentum. However, if we add up the momentum of various pieces, the sum total of momentum will be zero.


• Why is it easier to stop a tennis ball than a cricket ball, moving at the same speed? Explain.
Ans. It is easier to stop a tennis ball than a cricket ball, moving at the same speed because the momentum of the cricket ball will be more compared to the tennis ball as the latter's mass is higher than the former's mass hence force required to stop the tennis ball will be less compared to the cricket ball.

Read More

The Vagabond - Class 7 English

Summary of the poem

R.L. Stevenson's poem "The Vagabond" is about the life of a vagabond(wanderer). The narrator wants to live a carefree life amidst the heaven, the land, the birds, the river. He does not yearn for wealth, friends, love, hope. He stresses repeatedly that he only wants the heaven above and the road below him, so that he can go places without worrying about the comforts of life. Nothing can reduce his spirit of wandering. He speaks of harsh conditions in autumn and winter but these also cannot deter his yearn to be on road. He knows that he would die sooner or later but he as long as he is alive he only treausres to live his life on road, with heaven above and the road below.

---

Stanza wise Explanation

1^st Stanza

In the first stanza the narrator tells that he wants a carefree life and all he wants to do is travel from one place to another. He wants the great outdoors, with the sky as his roof and a road to travel. He wants his bed in the bush so that he can see the stars. The narrator wants a humble life and is happy to dip the bread in the river instead of cup of tea or coffe and this is the type of life he wants forever

2^nd Stanza

The narrator here says that even though the misfortunes of life may come to him still he wants to be carefree. He is ready to face difficulties along his path but he will not stop wandering around nature. He does nto want riches, love or friend. He only wants the sky/heaven above and the road below him.

3^rd Stanza

This stanza tells about the hardships of life staying outdoors in autumn and in winter. He says that let the leaves of autumn fall on him that represents the beginning of old age. In autumn, the field looks barren as the leaves have withered off trees. The birds around are silent and are no longer singing on the trees. The cold is severe in winter that blood freezes and fingers turn blue. The fields are snow laden. The fireside is the only place that can give some warmth and relief. However, the narrator further states that even such harsh conditions will not stop him from living in the open because all he years is freedom from anything else.

4^th Stanza

Same as second stanza.

---

Meaning of difficult words

Vagabond - Wanderer

Lave - A stream or a rivulet

Jolly - Merry

Nigh - Near, beside

Dip - To immerse

Seek - Look for

Afield - In the field

Linger - To remain for a long time

Haven - A safe place

Yield - Surrender

---

Questions and Answers

1. What does the vagabond ask for in the first stanza of the poem?

Ans. The vagabond asks for a simple and worthy life that he loves. A life that is not bound to material wealth or wordly pleasures. The vagabond wants the sky as his roof and a road to travel. He prefers to sleep in a bush in the open green fields of nature so that he can see the stars at night. He loves a humble life and is happy to dip his bread in the river instead of a cop of tea or coffee.

2. What does the vagabon not wish for?

Ans. The vagabond does not wish for any wealth of the world or any material benefits. He also does not wish for a friend to know him nor does he hope for love. He only wants the natural surroundings and the heavenly bodies to be with him throughout his existence on earth.

3. What does he say about autumn and winter?

Ans. The vagabond talks about the harsh conditions in autumn and winter that he may have to face while living in the open nature. He wishes that the autumn leaves would fall upon him when he is in the white field covered in frost and snow. In winter, he wants to bite his finger which has turned blue because of the severe cold. He states that even in these harsh conditions he would not stop wandering because he desires this free life with nature.

4. What do you think of the life of a vagabond? Would you desire such life for yourself?

Ans. A vagabond is a wanderer who has no roof over his head. He probably would have no friends, wealth, love. He would have to face the harsh conditions living a nomadic life, there would be many obstacles, hurdles paving in his way of life. I would not desire such a life as for me friends, love, emotions, comfort of of my home matters.

5. What kind of imagery do you think the vagabond evokes when he talks about his ideal life?

Ans. The vagabond evokes images or clear skies, starry nights, dipping bread in river, a road that is unending and takes him to places, autumn leaves falling, open fields covered with leaves in autumn and winter, warming himself in fireside.

6. Why do you think the poet repeats the lines. 'All I ask, the heaven above/And the road below me' in the second and fourth verses?

Ans. The poet repeats the lines 'All I ask, the heaven above/And the road below me' in the second and fourth stanzas because he stresses on his objective of leading a carefree life. He does not want material comforts or being bounded by emotions. All he wants is a heaven above him and roads to take him to places.

---

Word Wise

Replace the highlighted words in these sentence with their synonymns from the poem.

1. Camping by the river with happy little children is a wonderful experience.
Ans. jolly
2. He was prepared for the worst calamity.
Ans. blow
3. Dennis was told not to loiter and finish his project quickly.
Ans. seek
4. High up on the hills, this winter the fields were frozen.
Ans. frosty
5. The old woman was looking for a safe shelter to spend the night.
Ans. haven
6. The soldiers were advised never to surrender to their enemies.
Ans. yield

Read More

How to write a Notice (Notice Writing)

How to write a Notice, Class 9

Notice - A notice can be described as a written or printed information. It is written to provide information about an activity or an event.

An example of Notice

Borkhola Boy's School, Cachar

NOTICE

Celebration of Yoga Day

30th May, 2021

Students are informed that “Yoga Day” will be observed on 21^st June, 2021 in the school premises. Every student is requested to bring a “Yoga Mat”. For more information contact the undersigned.

Malay Das
Student Secretary

Key points to remember while writing a notice

• Formal/Polite language
• Avoiding quote, writing in passive voice
• Avoiding first person, second person
• Should be short/compact/precise in minimum words possible
• There should be a difference between date of issue of notice and date of event
• The content must include complete information we should try to incorporate the 7 W's (who, what, where, why, when, in what way and for whom) while writing the notice.
• The notice should be presented within a box

Read More

Active and Passive Voice

Active and Passive voice - Class 7, Class 9

Active voice - The form of the verb which shows the importance of its subject(doer of the action) is called the active voice.

Passive voice - The form of the verb which shows the importance of its object(receiver of the action) rather than the subject, it is called the passive voice.

---

General Rules to express a passive voice:

1. The Passive voice is formed by using appropriate forms of the verb be with the third form of the main verb.
2. The object takes the place of the subject.
3. The subject is either left out or mentioned at the end as a mere agent of the action done.
4. The verb does not change its tense, but its form only.
5. The preposition by is mostly used to show the subject as an agent of action. Sometimes other prepositions like to, with, at and in etc. are used in place of by.
6. Prepositions inseperable attached with the verb in the active voice are not dropped while using by.
7. There is no passive voice of the verbs used in Future Continuous tense and the three (Present/Past/Future)Perfect Continuous forms.

---

Rules :Chaning various forms of verbs from active voice to passive voice

Present Indifinite Tense - Passive voice is formed by using is, am, or are before the third form of the verb.

Present Continuous Tense - Passive voice is formed by using is or am or are + being + third form of verb.

Present Perfect Tense - Passive voice is formed by using has or have + been + third form of verb.

Past Indefinite Tense - Passive voice is formed by using was or were + third form of verb.

Past Continuous Tense - Passive voice is formed by using was + were + being + third form of the verb.

Past Perfect Tense - Passive voice is formed by using had + been + third form of verb.

Future Indefinite Tense - Passive voice is formed by using will/shall + be + third form of verb.

Future Perfect Tense - Passive voice is formed by using will/shall + have been + third form of verb.

Read More

Adjectives - Class 7 Grammar

Adjectives These are words used to desribe a noun or a pronoun.

---

Adjectives have two uses:

Attribute-Adjectives are said to be used attributively when they are placed close to and before the noun which they qualify. Example - A good boy, A red ball. An adjective so used is called an Epithet

Note:A few adjectives such as former, olden, etc. can be used only attributively.

Predicative-Adjectives are said to be used predicatively when they express what is declared of some person or thing, and come after the verb. Example - The boy is good, The ball is red
NoteThere are a few adjectives such as alone, asleep, afraid, alike, aloof, alive, ashamed, awake, aware, content etc. which can only be used predicatively

---

Classification of Adjectives:

1. Proper - These are derived from some Proper Nouns such as Indian, British, Vedic etc.
2. Class - These describes the class or category to which the noun belongs. Example - Dowry is a social evil, We are in need of a financial help, We have many religious festivals
3. Color - These describes the color of its noun. Example - She has brown hair and blue eyes, Neena is wearing a pale green top.
4. Precision - These are used before the main adjective to make the description precise. Example - Your success in the last tough meeting is amazing, He is the only living heir to the throne.
5. Qualitative - These describe the quality or state of a thing. Exmaple - He is an honest boy, The brave man faced the angry crowd, This is a large city, The foolish old crow tried to sing.
6. Quantitative - These describe the quantity or number. Example - some, little, first, two, many, any, all, whole etc.
7. Distributive - These are used to refer to each and every person / thing separately. Example - each, every, either, neither, any, both etc.
8. Demostrative - These used to identify or express the relative position of a noun in time or space. Example - this, that, such, same, those etc.
9. Interrogative - These describes a noun that is used in a question. Example - which, whose, what, when, whose etc.
10. Emphasizing - These are used to emphasise statements. It heightens or reduces the effect of the noun they are modifying. Example - own, very etc.
11. Adjective Substitutes - An adjective substitute is not a natural adjective. It only functions as an adjective. Example - What an amusing show?, The dying man gave a statement, He is a known writer of books.
12. Compound - A compound adjective is made up of two or more words usually written with a hypen in between. Example - She is a good-looking girl, The built-up area is too small, I want a clear-cut answer to the question.

---

Comparision of Adjectives

Positive Degree - The positive degree is the simplest form of the adjective. Example - tall, beautiful.

Comparative Degree - The comparative degree is the form used when a comparision is made between two persons or things. Example - He is taller than you., It is more beautiful than that.

Superlative Degree - The superlative degree is the form used when more than two things, or sets of things are compared. Example - He is the tallest boy in the class, She is the most beautiful of all.

---

Rules of Comparision

Adjectives of one syllable are compared by adding er and est in the Comparative and Superlative degree respectively.

Exceptions

1. When the Positive ends in e, the e of er and est is dropped. Example - wise - wiser, wisest; pale - paler, palest.
2. Whe the Positive ends in y preceeded by a consonant, y is changed into "i" before er and est. Example - dry - drier, driest.
   But when a vowel precedes y, it is not changed. Example - gay - gayer, gayest.
3. If the Positive degree ends in a single consonant preceded by a single vowel, the consonant is doubled. Example - red - redder, reddest.
   But if it ends in two consonant, or has two vowels before the final consonant, the latter is not doubled. Example - thick - thicker, thickest; weak - weaker, weakest.

Adjectives of more than two syllables and most adjectives of two syllables are compared by adding more and most or less and least. Example - beautiful - more beautiful, most beautiful; active - more active, most active

All adjectives of two syllables ending in le, y, er and ow are generally compared as adjectives of one syllable

---

Comparisions

Positive	Comparative	Superlative
Noble	Nobler	Noblest
Happy	Happier	Happiest
Tender	Tenderer	Tenderest
Narrow	Narrower	Narrowest

Irregular Comparison

Positive	Comparative	Superlative
Bad, evil, ill	Worse	Worst
Far	Farther	Farthest
Good	Better	Best
Late	Later, Latter	Latest, Last
Little	Less, Lesser	Least
Many, much	More	Most
Near	Nearer	Nearest
Old	Older, elder	Oldest, eldest

Questions and Answers

1. What is the positive degree of an adjective used for? Give two examples
Ans. The positive degree of an adjective is used to express a quality in a simple positive way, i.e., only against a negative sense.
Example - Ramu is an honest servant.
Reeta is a charming girl.
2. What is the comparative degree of an adjective used for? Give two examples
Ans. The comparative degree of an adjective is used to compare two persons, things or groups etc. It is always followed by than.
Example - Ramu is more honest than Raju.
Reeta is more intelligent than Geeta.
3. What is the superlative degree of an adjective used for? Give two examples
Ans. The superlative degree of an adjective is used to compare a person or thing with a group. It is preceeded by the and followed by of or in.
Example - Ramu is the most honest of all servants.
Reeta is the most charming of all girls.
4. By what word is the comparative degree of an adjective generally followed?
Ans. The comparative degree of an adjective is generally followed by than.
5. By what word is the superlative degree of an adjective generally preceeded?
Ans. The superlative degree of an adjective is generally preceeded by the.
6. When is the not used before a superlative degree?

Ans. The is not used before a superlative degree in the following cases:

When a possessive word precedes the superlative degree.
Example. He is my best friend.
Rajesh has done his best.

When no comparision is meant but only a very high degree of quality is meant.
Example - This is most unfortunate.
That was most unwise on your part.

---

1. What is an adjective? Name its kinds
Ans. An adjective is a word that adds to the meaning of a noun.
The different kinds of adjectives are:
1. Adjectives of Quality
2. Proper Adjectives
3. Class Adjectives
4. Color Adjectives
5. Emphasizing Adjectives
6. Precision Adjectives
7. Adjective Substitutes
8. Compound Adjectives
9. There are no numeral, quantative and interrogative adjectives as these have become determiners(determiners are words placed in front of a noun to make it clear what the noun refers to) now.
2. What is an adjective of quality?Give five examples
Ans. An adjective of quality denotes some quality of its noun.
Example - Abdul Majid was a brave soldier
His watch has a golden chain
The Taj Mahal is a wonderful building
Delhi is an ancient city
An honest person is respected everywhere.
3. What is a proper adjective?Give five examples
Ans. A proper adjective is formed from a proper noun.
Example - The Gangetic plain is very fertile
The Indian nation is a great nation
European people are mostly fair
Fahien was a Chinese piligrim
The Turkish Empire was very vast.
4. What is a color adjective?Give five examples
Ans. A color adjective describes the color of its noun.
Example - She has brown hair and blue eyes
Rajesh wore a white shirt
Black color absorbs light
Your face looks redder than yesterday
White color radiates light
5. What is an emphasizing adjective?Give five examples
Ans. An emphasizing adjective lays stress on a fact about its noun.
Example - He looks a complete idiot
We are strict vegetarians
Netaji Subhash Chandra bose was a true patriot
What was the total expenditure to build your house?
I am reeling under utter despair
6. What is a precision adjective?Give five examples
Ans. A precision adjective is used before the main adjective to make the description precise.
Example - Your success in the last tough examination was outstanding
The old man was in his unusual white suit
He is the only living heir to the throne
Certain basic needs are common
You have told the same old story again.
7. What is an adjective substitute?Give five examples
Ans. An adjective substitute is not a natural adjective. It only functions as an adjective.
Example - The dying man gave a statement
That bearded man is my uncle
I have bought a furnished flat
Her pleasing manners are nice indeed
There is an alarming increase in expenses.

Read More

How to find Square Root of Numbers

Square root by Factorization

Square root by Approximation

Square root by Long Division Method

Square, cube, square roots of numbers 1 to 50

Read More

Respiration in Organisms - Class 7 Science

Respiration-The biological process in which food is utilized to produce energy is called respiration. Respiration is necessary for the survival of all living beings.
Carbohydrate + Oxygen → Carbon dioxide + Water + Energy

Types of Repiration

Aerobic respiration-Aerobic respiration takes place in the presence of oxygen. Carbon dioxide and water are the end products.
Glucose + Oxygen → Carbon dioxide + Water + Energy

Anaerobic respiration-Anaerobic respiration takes place in the absence of oxygen.It usually happens in microbes. Alcohol and carbon dioxide are the end products.
Glucose(in absence of oxygen) → Alcohol + Carbon dioxide + Energy

---

Lactic acid-Anaerobic respiration also happens in our muscle cells. When someone runs or walks too fast, one may feel a throbbing pain in the calf muscles. This happens because of deposition of a chemical compound called lactic acid.If we take rest for sometime the pain goes away as the supply of oxygen increases which breaks down the lactic acid into carbon dioxide and water
Glucose(in absence of oxygen)→Lactic Acid + Energy

---

Breathing- The process of taking in and giving out air for respiration is known as breathing

Human Respiratory System

Nasal passage

Oral cavity

Pharynx

Larynx

Trachea

Bronchi

Lung

Heart

Ribs

Inhalation-Inhalation is the process where we breathe in air rich in oxygen

Exhalation-Exhalation is the process where we breathe out air rich in carbon dioxide

Breathing rate-The number of time a person breathes in a minute is known as breathing rate

How do we breathe?

The process of breathing takes place in our lungs

The process of breathing is controlled by the movement of diaphragm

Diaphragm is a membrane present between the chest and abdomen.

The movement of diaphragm is controlled by a group of muscles known as intercostal muscle.

When the diaphragm moves down the ribcage expands. This leads to the expansion inside the lungs. As a result, the air moves into the lungs. This process is known as inspiration or inhalation

When the diaphragm moves up the ribcage contracts. This leads to the contraction of the lungs. As a result, the air moves out of the lungs. This process is known as expiration or exhalation

Repiration in plants

In plants the external layer of cells can breathe, roots breathe through root hairs, stems breathe through epidermis, leaves have numerous small pores called stomata for breathing.

Breathing in other animals

Flatworms- Flatworms use their outer surfaces as gas exchange surfaces

Earthworms- In earthworms gas exchange occurs at capillaries(a series of thin-walled blood vessels)

Unicellular organisms(amoeba, paramecium)-Unicellular organisms exchange gases through their cell membrane

Amphibians - Ambphibians use their skin and lungs

Terrestrial animals - Many terrestrial animals have their respiratory surfaces inside the body and connected to the outside by a series of tubes. These tubes are known as tracheae. Spiracles are openings at the body surface that lead to tracheae. Tracheae branch into smaller tubes known as trachcoles.

Fish - Fist breathe oxygen dissolved in water through gills

Respiratory system principle

Process of respiration is completed by the following steps:

1. Movement of an oxygen-containing medium so it contacts a moist membrane overlying blood vessels
2. Diffusion of oxygen from the medium into the blood
3. Transport of oxygen to the tissues and cells of the body through blood
4. Diffusion of oxygen from the blood into cells
5. Carbon dioxide follows a reverse path and moves out of the body

Objective Type Questions

A.Fill in the blanks.

1. Aerobic respiration takes place in the presence of oxygen.
2. Alcohol and carbon dioxide are the end products of anaerobic respiration.
3. A person feels a throbbing pain in the calf muscles due to the production of lactic acid
4. The number of times a person breathes in a minute is known as the breathing rate
5. The movement of diaphragm is controlled by a group of muscles known as the intercostal muscles
6. Earthworms have a series of thin-walled blood vessels known as capillaries
7. Tracheae branch into smaller tubes known as tracheoles
8. Each plant breathes through its external layer of cells

B.True and False.

1. Taking in air is exhalation - F
2. Amphibians breathe through skin as well as lungs - T
3. Anaerobic respiration needs oxygen - F
4. Respiration is a process in which engery is released - T
5. Our nose filters oxygen from air - F

C.Correct answer.

1. Aquatic animals get the oxygen from - air and water
2. Organism that does not need oxygen to survive - yeast
3. Anaerobic respiration produces - Carbon dioxide and energy
4. When we run there is a deposition in muscle cells known as - Lactic acid
5. When we blow air into a test tube containing limewater, the limewater turns milky.This happens because of reaction of limewater with - carbon dioxide

Very Short Answer Questions

D.Answer the following in brief.

1. Name the respiratory organs in humans.
Ans. Nose, Mouth, Larynx, Pharynx, Lungs and Diaphragm.
2. Which membrane controls the movement of lungs?
Ans. Diaphragm
3. Which is the respiratory organ in fish?
Ans. Gills
4. What is the respiratory organ in cockroach?
Ans. Spiracles
5. Which organ is used by a frog for breathing under water?
Ans. Skin
6. What is the end product of respiration in most of the organisms?
Ans. Carbon dioxide, water and energy
7. What is the end product of anaerobic respiration in muscle cells?
Ans. Alcohol, carbon dioxide and energy

Short Answer Questions

E.Define the following

1. Breathing
Ans. Breathing is the process by which air rich in oxygen is taken inside the body of an organism and air rich in carbon dioxide is expelled out from the body with the help of lungs.
2. Respiration
Ans. The biological process in which food is utilized to produce energy. It is also the process of releasing energy from food. The process of respiration involves taking in oxyge from air into the cells and then eliminating the waste products(carbon dioxide and water) from the body.
3. Inhalation
Ans. When the diaphragm moves down the ribcage expands. This leads to the expansion inside the lungs. As a resut, the air moves into the lungs. This process is known as inhalation.
4. Exhalation
Ans. When the diaphragm moves up the ribcage contracts. This leads to the contraction of the lungs. As a resut, the air moves out of the lungs. This process is known as exhalation.

F. Differentiate between the following

1. Respiration and breathing
2. Aerobic and Anaerobic respiration
3. Gills and Tracheae
4. Inhalation and Exhalation

G.Answer the following in brief

1. What is cellular respiration?
2. When we run or walk fast, we feel throbbing pain in calf muscles. Why? How it can be relieved?
3. How do frog respires in water and land?
4. Why is it suggested not to overwater plants?

Read More

Weathering and Erosion - Class 7 Geography

Weathering - Weathering is the breaking up of rocks on or near the Earth’s surface.

Types of Weathering

Physical weathering -It is the breaking or fracturing of rocks due to temperature change, frost action, salt formation in drier areas. It is helped by the growth of plants in rocks and the burrowing of animals. The rock simply breaks and there is no decay.

Chemical weathering -It happens when there is a chemical change in the rock structure and new minerals are formed. This sort of weathering is more common in warm, moist climates. Chemical weathering causes rock decay

Erosion -Erosion is the process of wearing away of the land by natural agents such as running water, ice, wave action and wind.

Denudation -Erosion removes the soil and rock debris and ceases them away leading to a reduction in elevation and in relief of landforms and of landscapes.

Difference between weathering and erosion

Weathering	Erosion
It is the breaking of rocks	It is the displacement of rock debris, soil
It is caused by physical and chemical factors, plants growing on rocks, burrowing done by animals	It is caused by running water, glaciers, waves, wind
The weathered materials are not displaced	The eroded materials are displaced

Difference between erosion and denudation

Erosion	Denudation
Erosion is the transport of soil and rocks from one location to another	Denudation is the sum of processes that result in the lowering of the Earth's surface, including erosion

Types of Erosion

Aggradation -Aggradation is the process by which a landform is built by the deposition and accumulation of material. Example – An alluvial plain.

Degradation -Degradation is the process of lowering a surface by erosion and the removal of rock water. Example - Pedestal rock.

Types of Erosional Agents

Running Water - Includes rivers or streams.

Three steps in the life of a river

Youth - In its youth, the river flows very fast through narrow channels and erodes the sides forming V-shaped valleys, gorges or canyons. It is generally seen in mountainous areas where the slope of the land is steep. There is no depositionat this stage.

Middle stage-In the middle stage the slope of the land becomes gentler and the river also slows down. Here, the river starts depositing the heavy load that it carries. Its valleys now become broader and wider also the river starts winding to go around the material it has deposited. Here both erosionand depositionoccurs.

Meanders-The bends of the river are called meanders.

Floodplains-The depositional plain formed in between the meanders are called floodplains.

Last stage-In the last stage the river becomes even slower with the decreasing slope of land. The river valley is very broad at this stage. It is here that river forms a delta at the mouth of the seas. The river deposits all the remaining debris it contains here and then splits into small streams, avoiding the deposition to reach the sea. This stage is marked by depositiononly.

Delta-Deltas are wetlands that form as rivers empty their water and sediment into another body of water.The Ganga-Brahmaputra Delta is the biggest delta in the world.

Estuary-The part of river where it joins the sea and where fresh water of river and saline water of sea is mixed is called Estuary.

Distributary-Distributary channel is a stream that carries water away from the main river channel and distributes it to other area.

Tributary- Tributaries are small streams of water that join the mainstream river to increase its water supply.

Stream-A small narrow river.

Wind - Wind is another erosional agent, wind picks up loose material in its path and rolls them along the ground.

Sand Dune-The transportation and deposition of soil by wind in desert causes soil to pile and create a hill of soil, this is known as sand dune

Barchan-The sand dune keeps changing shape when wind blows, when sand dune takes the shape of crescent it is known as barchan

Loess-In mid-latitude areas, the wind has transported silt(rock debris) to form large surfaces with it. This is called loess

Glaciers - Glaciers are also a cause of erosion

Glaciers-Large blocks of ice that move forward under their own weight are called glaciers.These can be found where snowfall is high, such as high mountains like the Himalayas, or in the polar regions like the Antarctica.99% of glaciers are found in Antarctica and Greenland.

Moraine-Mountain glaciers carry debris of rocks in their lower parts, and the accumulation of such debris is called moraine.

Glacial Troughs-The glaciers form steep-sided wide valleys which seem to be U-shaped. These valleys are called Glacial troughs

Cirques-There are smaller troughs, with steep walls which are called cirques.

Tarns-In many glaical troughs some lakes are formed, these lakes are known as tarns

Fjords-Glaciers also form narrow deep valleys with steep sides called fjords

Icebergs-When glaciers break and huge blocks of ice drift into the sea then those huge blocks of ice are known as icebergs.

Waves - Waves are another factor that cause erosion

Waves - Waves are large bodies of water that form a ridge and move forward on the water surface by the action of wind. The waves shape the landform on the coasts. Waves carry out deposition and erosion

Arch - When waves cut through a cliff then archs are formed

Stack - When the arch breaks down, the rock column that remains is called the stack

Marine cliffs-When the wave breaks on the coastline, many tons of water fall on it. If the rock is weak, the coasline will be eroded rapidly and these leads to the formation of marine cliffs

Sea caves-The points of weakness in the cliffs get cut back by the waves and deep gaps or sea caves are formed in those cliffs

Beach-When waves bring along with them sand and when lots of sand deposits to form a thick surface then such thick surfaces of sand are known as beaches

Read More

Motion - Class 9 Science

Motion - Motion is the movement of any object from one point to another with respect to observer. An object is said to be in motion when it changes its position with time.

Rest - A body is said to be at rest if it does not change its position with respect to its surroundings with time.

Different Types of Motion

Linear Motion - Linear motion is a motion in which a body moves in a straight line. Example - Marchpast by soldiers, A car moving on a straight road.

Circular Motion - Circular motion is a motion in which a body moves along in a curved path. Example - Motion of satellites around planets, A car moving in a traffic roundabout

Rotational Motion - Rotational motion is a motion in which a body rotates about a fixed axis. Example - Motion of wheels around vehicles, Spinning of a top

Vibratory Motion - Vibratory motion is a motion in which a body moves in a to and fro direction. Example - Motion of a simple pendulum, Motion described by the string of a violin when

Rest and Motion are relative terms - Rest and motion are considered as relative terms because they both depend on observer's frame of reference.

Uniform motion - When an object covers equal distance in equal intervals of time.

Non-uniform motion - When an object covers unequal distance in equal intervals of time.

Circular motion - Circular motion is the movement of an object along the circumference of a circle or rotation along a circular path.

Uniform circular motion - Uniform circular motion can be described as the motion of an object in a circle at a constant speed.

Non-uniform circular motion - Non-uniform circular motion denotes a change in the speed of a particle moving along a circular path.

Direction of motion at any point in a circular path - As an object moves in a circle, it is constantly changing its direction. At all instances, the object is moving tangent to the circle.

Equation of speed in a uniform circular motion, if the radius of the circle is r and time taken is t: v = circumference/time or v = 2πr/t, Note - Here v is scalar and not vector.

Circumference of Circle = 2πr (r is the radius of the circle)

Difference between Circular motion and linear motion

Circular motion	Linear motion
In circular motion, the speed is constant but the direction of the object changes continuously, hence it is accelerated	In linear motion, the speed and direction of the object is fixed and so it is not accelerated
Motion of earth around the sun	A car moving on a straight road

Magnitude - Magnitude is the size or extent of a physical quantity.

Scalar quantity - Scalar quantity are only expressed only in magnitude. Example - Time, Distance, Mass, Temperature, Length, Area, Volume etc.

Vector quantity - Vector quantity are expressed in magnitude as well as the direction of the object. Eg. Velocity, Displacement, Weight, Force, Acceleration etc.

Difference between scalar and vector quantity

Scalar Quantity	Vector Quantity
They are expressed in magnitude only	They are expressed in magnitude and direction
They can be added by simple arithmetic means	They cannot be added by simple arithmetic means
They cannot be easily plotted on graph	They can be plotted on graph
They are one dimensional	They are multidimensional
Area, Pressure, Density, Temperature, Mass	Momentum, Force, Acceleration, Displacement, Velocity

Distance - It is the actual length of the path travelled by a moving body irrespective of the direction in which the body moves.

Displacement - The shortest distance of a moving body from the point of reference(initial position of body).

Difference between Distance and Displacement

Distance	Displacement
It is the actual length of path travelled by a moving body	It is the shortest distance between the initial and final position of the body
It has only magnitude(scalar quantity)	It has both magnitude and direction(vector quantity)
It is always positive	It may be positive, negative or zero
SI unit of distance is m	SI unit of displacement is m

Speed - Speed is the defined as the distance covered in unit time. Speed = Distance/Time

Average Speed - Average speed is the total distance travelled in a particular interval of time or we can say average speed is the total distance travelled in total time interval. Average speed = Total Distance/Total time

Uniform speed - When the distance travelled by a body is equal in equal interval of time.

Non-uniform speed - When the distance travelled by a body is unequal in an equal interval of time.

Velocity - Velocity is the displacement of the object in unit time. Velocity is speed with direction. Example - Car moving at 40km/h is its speed whereas the car moving at 40km/h westward is the velocity

Difference between speed and velocity

Speed	Velocity
Speed is the distance covered in unit time. Speed = Distance/Time	Velocity is the displacement covered in unit time. Velocity = Displacement/Time
Speed is a scalar quantity	Velocity is a vector quantity
Speed is rate of change of distance	Velocity is rate of change of displacement
Speed can never be zero	Velocity can be positive, negative, zero
SI unit of speed is m/s	SI unit of velocity is m/s

Acceleration(a) - Rate of change of velocity, a = change of velocity/time or, a = (v - u)/t, here v - final velocity, u - initial velocitySI unit of acceleration is m/s²

Uniform acceleration - Uniform acceleration is the acceleration in which the velocity of a body changes at a constant rate in a given interval of time.Example - Motion of a ball dropped from a height.

Non-uniform acceleration - Non-uniform acceleration is the acceleration in which the the velocity of a body does not change at a constant rate in a given interval of time.Example - A car travelling 60 km in 1 hour and 70 km in 2^nd hour

Equations of motion

v = u + at

s = ut + 1/2 at2

v2 = u2 + 2as

Read More

Palm Tree - Class 7 English

Palm Tree - By Rabindranath Tagore

Summary of the poem “Palm Tree” by Rabindranath Tagore

Palm Tree by Rabindranath Tagore is an imaginative poem in which the poet shows the feelings and aspirations of a Palm tree. The poet feels that the Palm tree has a longing to go beyond the ceiling of grey clouds in the sky, it wants to fly away but sadly it has no wings. After the wind stops the tree appears to have realized that it belongs to earth that is its mother and then it stands quietly. Through the poem the poet teaches the moral value that we should be fond of what we are and we should not try to become someone else.

---

Questions and Answers

1. The poem vividly describes the movement of the tree in a wind. Complete the sequence chart to trace the movement.
Ans - The tree raises itself over other trees – The tree spreads its fronds like wings to fly – Flies in his own mind across the skies – Finally the wind is still and the tree returns to mother earth.

---

2. Read these lines and answer the questions that follow.

a. The palm tree stands
   On one leg, sees
   Past other trees
   Into the sky 

1. These lines tell us that the tree is:
Ans. Taller than other trees
2. What does one leg signify? What is the poetic device used here?
Ans. One leg signifies the trunk of the tree, the poetic device used here is personification.
3. What is the action that the poet imagines the tree doing?
Ans. The poet imagines the tree to be flying in the sky.

---

    
b. At length his wish
   He starts to spread
   Around his head
   In big sound, fronds:

1. What according to the poet, does the tree wish?
Ans. The tree wishes to pierce the clouds and soar away.
2. In the poet’s imagination, what does the tree think about its fronds?
Ans. The tree thinks that the fronds are its wings.
3. What does the poet compare the palm tree to? How apt or suitable is this comparison?
Ans. The poet compares the palm tree to a bird. It may be suitable to some extent because the Palm tree is a tall tree and when it sways with the wind, it seems to be touching the sky.

---

c. But when the wind
   Is still at last
   And the leaves hushed.
   Back homeward then
   He turns his thoughts

1. Where do the thoughts of the tree turn?
Ans. The thoughts of the tree turn back towards home to the earth from the sky.
2. What does the poet mean by when the wind/Is still?
Ans. By when the wind/Is still, the poet means that the wind has stopped blowing.
3. Where was the mind of the tree before this?
Ans. The mind of the tree was in the sky and clouds, soaring with the winds, before this.

---

3. What is the poem about? In two or three lines, summarize the subject of the poem.
Ans. The poem is about a Palm tree that wants to get away from home and wander in other lands. In other words, it talks about those who want to explore new places. The poem highlights the fact that whatever you do and wherever you go when the fire within you dies, when the wind stops blowing you, you will realize that there is no place like home.

---

4. What is the mood or atmosphere of the poem? Does it sound happy, sad, defiant, thoughtful, triumphant or unemotional?
Ans. The mood or atmosphere of the poem is defiant (defy - Appear to be challenging (someone) to do or prove something). The poem starts on a defiant note where the tree wants to fly irrespective of the fact knowing that it is rooted to the earth but at the end when the wind stopped blowing realization stuck so it became grounded.

---

5. Does the poet offer us a message or a point of view through this poem? If so, what is it?
Ans. The poet talks about loving your motherland despite having big dreams and aspirations. He says that it is always comforting to return to your motherland.

---

Read More

Lines and Angles - Class 7 Maths

Some important points

Line segment - A line segment is a portion of a line that has two end points

Line - A line is a straight path of points that has no beginning or end

Point - A point has not size or shape, it has just position

Angle - An angle is formed when two lines or line segments meet

Arms of an angle - The lines or line segments which forms an angle are called its arms

Vertex of an angle - The meeting point of the lines or line segments is called the vertex of an angle

Acute angle - An angle greater than 0° but less than 90° is called an acute angle

Obtuse angle - An angle greater than 90° but less than 180° is called an obtuse angle

Right angle - An angle which measures 90° is called a right angle

Straight angle - An angle which measures 180° is called a straight angle

Reflex angle - An angle which is more than 180° but less than 360° is called a reflex angle

Complete angle - A complete angle is equal to 360°

Adjacent angles - Adjacent angles have the same vertex a common arm and two non-common arms

Complementary angles - When the sum of two angles is 90°, the angles are called complementary angles and each angle is said to be complement of the other angle

Supplementary angles - When the sum of two angles is 180°, the angles are called supplementary angles and each angle is said to be supplement of the other angle

Read More

Idioms and Phrases

Abide by - (remain faithful to): You must abide by the terms of your contract

To abound in – (to be plentiful): India abounds in wheat

To abound with – (be infested with): The city abounds with police patrolling the streets because of lockdown

To beat about the bush – (repeat the same point): Please do not beat about the bush, tell me what you want to say

Hang about – (hover): Do not let unknown persons hang about your house

Out and about – (restored to normal activity after illness): I hope my friend suffering from cold and cough will be out and about in a week

Dotted about – (covered): Due to the cyclone Tauktae, plastic waste is dotted about the sea coast of Gujarat

To come about – (happen): Many changes have come about in India after the attainment of Independence

Over and above – (in addition to): He gets a bound on sales over and above his salary

In accordance with – (in arrangement with): In accordance with your request, I am sending the book you had asked for

On account of – (because of): On account of my sickness, I could not attend school

To gain an advantage – (to acquire): On account of strategic planning by Indian Government we have somewhat managed to curb the catastrophe caused by Covid-19

Look before and after – (waste time in vain regrets on dreams): A successful person does not look before and after

From afar – (at a great distance): All gifts look beautiful from afar

After one’s heart – (such as one loves): This house is after my heart

Time and again – (repeatedly): The teacher time and again asked the students to complete their daily homework

To agree with – (suit): The summer season of Delhi does not agree with me

To build castles in the air – (visionary objects): Do not build castles in the air

Air of absurdity – (appearance of foolishness): He has an air of absurdity about him

With a triumphant air – (show the victory): He entered the house with a triumph

All and sundry – (individually and collectively): All and sundry came to the meeting

To lead to the altar – (to marry): He led a beautiful woman to the altar

Answer to the door – (meet a caller): When at home I usually answer to the door

At any rate – (in any case): At any rate, I cannot go out of my house because of strict lockdown

Apple of the eye – (any cherished object): My sister is an apple of the eye for our family

With open arms – (cordially): They welcomed us with open arms

Keep at arm’s length – (avoid familiarity): We must keep strangers at arm’s length

Lay down arms – (cease hostilities): The soldiers refused to lay down their arms

 

Read More

Polynomials - Class 9 Maths

Constant - The symbol which has a fixed numerical value is called a constant

Variable - The symbol which assumes different values in different situations is called a variable

Coefficient - A numerical or constant quantity before the variable

Operator - The symbol of a mathematical operation

Exponent - A number or a value or letter written above and to the right of a mathematical expression

Algebraic Expression - The combination of constants and variables by the use of some or all operations as x²+5y-7

Terms - The various parts of an algebraic expression seperated by operators are called terms of the algebraic expression

Polynomial - An algebraic expression is called a polynomial if the variable involved have only non-negative integral powers as 7x³-5x²+6x-9

Degree of a Polynomial

(i)When the polynomial is in one variable - In this case, the highest power of the variable is called the degree of the polynomial.
  Example - 7x2+x is a polynomial in x whose degree is 2
  7y3+y is a polynomial in y whose degree is 3
 (ii)When the polynomial is in two variable - In this case, the sum of the powers of the variables in each term is taken up and the highest sum, so obtained, is called the degree of the polynomial.
  Example - 5x2y3-5x4y3-3x2y2, Note carefully for the first expression the sum of the powers is 5, for the second expression the sum of the powers is 7 and for the third it is 4, as 7 is the highest sum so the degree of x and y is 7
  For multiple variables, we follow the above step.

Types of Polynomials

• Zero Polynomial - A polynomial which consists of 0 only is called a zero polynomial. The degree of a zero polynomial is not defined.
• Constant Polynomial - A polynomial which consists of only one constant term is called a constant polynomial. The degree of a constant polynomial is zero. Each real number is a constant polynomial. Example 5, -7/8, -3 are constant polynomials
• Linear Polynomial - A polynomial of degree one is called a linear polynomial. Example 5x+7 is a linear polynomial in x, 5x + 7y + 6 is a linear polynomial in x and y
• Quadratic Polynomial - A polynomial of degree two is called a quadratic polynomial. Example 5y²+7 is a quadratic polynomialin y, xy + x + 2 is a quadratic polynomial in x and y
• Cubic Polynomial - A polynomial of degree three is called a cubic polynomial. Example 5x³+2x²+6 is a cubic polynomial in x, 5x²y+4xy²+5 is a cubic polynomial in x and y
• Biquadratic Polynomial - A polynomial of degree four is called a biquadratic polynomial. Example 5x⁴+8 is a biquadratic polynomial in x, 5x³y+6xy³+7 is a biquadratic polynomial in x and y

Number of terms in a Polynomial

• Monomial - A polynomial which has only one non-zero term. Example 5, -7
• Binomial - A polynomial which has only two non-zero terms. Example 5 + 7x, x - 7y, 3x²y+2xy has
• Trinomial - A polynomial which has only three non-zero terms. Example 5+7x+x², xy+yz+zx

Exercise 2(a)

Exercise 2(b)

Read More

Acids, Bases and Salts - Class 7 Science

Acids are sour in taste, bases are bitter in taste and soapy to touch.

Acids turns blue litmus red and bases turn blue litmus red.

Sustances which are neither acidic nor basic are called neutral.

Solutions of sustances that show different color in acidic, basic and neutral solutions are called indicators.

An acid and a base neutralize each other and form a salt. A salt may be acidic, basic or neutral in nature.

Exercises

Q1. State differences between acids and bases

Answer - The differences between acids and bases are:

  

    
Acids
    
Bases
  
  

    
Acids are sour in taste
    
Bases are bitter in taste
  
  

    
Acids turn blue litmus red
    
Bases turn red litmus blue
  
  

    
Acids do not give soapy touch
    
Bases are soapy to touch
  

Q2. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. What is its nature?

Answer. As ammonia turns red litmus blue so it is basic in nature.

Q3. Name the source from which litmus solution is obtained. What is the use of this solution?

Answer. Litmus solution is extracted from lichens. It is used to determine the solution is neutral/acidic/basic. It has a mauve (purple) colour in distilled water. When added to an acidic solution, it turns red and when added to a basic solution, it turns blue.

Q4. Is the distilled water acidic/basic/neutral? How would you verify it?

Answer. We take two test tubes and add distilled water in those tubes. Once done we add blue litmus paper in one test tube and in the other we add red litmus paper, we observe that there is no change in color, so we can confirm that distilled water is neutral in nature.

Q5. Describe the process of neutralisation with the help of an example.

Answer. Neutralisation is a process where an acid and a base react to give salt and water. Let us take Hydrochloric acid(HCl) and a base Sodium hydroxide(NaOH) and react them, then we get
HCl + NaOH - NaCl(Sodium Chloride)+H 2O(Water)

Q6. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Nitric acid turn red litmus blue. (T/F) - F
(ii) Sodium hydroxide turns blue litmus red. (T/F) - F
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and
form salt and water. (T/F) - T
(iv) Indicator is a substance which shows different colours in acidic
and basic solutions. (T/F) - T
(v) Tooth decay is caused by the presence of a base. (T/F) - F

Q7. Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Answer. Dorji can decide in two ways, first he can taste a little part of the drinks for the drink which is sour then it will be acidic, for the drink which is bitter then it will be basic and the neutral drink will have no taste. Secondly if he has a litmus paper with him then he can put the litmus paper in a drink if the blue litmus paper turns red then it is acidic, if the red litmus paper turns blue then it is basic and if the drink shows no change in color with litmus paper then it is neutral.

8. Explain why:
(a) An antacid tablet is taken when you suffer from acidity.
(b) Calamine solution is applied on the skin when an ant bites.
(c) Factory waste is neutralised before disposing it into the water bodies.

Answer (a). An antacid contains bases which neutralizes the acidity and thus we feel relief from acidity.
(b). When an ant bites it injects formic acid in skin and calamine solution is basic in nature so it neutralizes the effect.
(c). Some factory waste contains acids and if they are disposed directly into water bodies then aquatic life will be harmed to prevent any harm from occuring to the aquatic life; factory waste is neutralized with a base.

Read More

Pronouns - Class 7 Grammar

Pronoun - A pronoun is a word used in place of a noun to avoid its repetition.

Pronouns are of 8 different kinds:

1. Personal Pronouns
2. Indefinite Pronouns
3. Interrogative Pronouns
4. Relative Pronouns
5. Demonstrative Pronouns
6. Distributive Pronouns
7. Reflexive Pronouns
8. Emphatic Pronouns

---

Personal Pronouns - Pronouns that indicate person, thing, animal, place etc. are called personal pronouns.
Example. Gody wants to talk to you
The horse was moving its tail.

In English Grammar, there are three types of persons
(i)First Person, (ii)Second Person, (iii)Third person
First Person - The speaker is the first person. I, we, me, us, my, our, mine and ours are pronouns of the first person.
Second Person - The listener is the second person. You, your and yours are pronouns of the second person.
Third Person - About whom/which the speaker is saying something. He, she, it, they, him, her, them, his, its, their are pronouns of the third person.

Persons	Subject	Object	Possessive	Reflexive
First Person	I	Me	My	Myself
	We	Us	Our	Ourselves
Second Person	You	You	Your	Yourself/Yourselves
Third Person	He	Him	His	Himself
	She	Her	Her	Herself
	It	It	Its	Itself
	They	Them	Their	Themselves

Subject - The Subject is a word, or a group of words, that denotes the person or thing about whom or which something is said. It must be a noun or a noun-equivalent, and may consist of any number of words.
Object - An object is the person, place, thing that receives the action.
Possessive - The possessive pronoun form is used with nouns referring to people, groups of people, animals etc.
Reflexive - Reflexive refers back to the subject of the clause in which it is used.

---

Indefinite Pronouns - Pronouns that show an indefinite or an uncertain number of people, person, thing etc.
Example - All, none, some, any, much, more, one, many, other, someone, somebody, anybody, anyone etc.

---

Interrogative Pronouns - Pronouns that are used to ask questions are called interrogative pronouns.
Example - Who, whom, whose, what, which, where, when, why, how, wherever etc.

---

Relative Pronouns - Pronouns that are used to join two sentences and reveal the noun that comes before it.
Example - I know the man who is a fighter.
I like the book that has a hologram.
Uses of some Relative Pronouns

(i)Who - For persons in the nominative case
(ii)Whom - For persons in the objective case
(iii)Whose - For persons in the possessive case
(iv)Which - For things
(v)That - For persons as well as things

---

Demonstrative Pronouns - Pronouns that are used to show or to indicate some nouns are called demonstrative pronouns
Example - This, that, these, those
Uses of some Demonstrative Pronouns

(i)This - For a single noun when it is near
(ii)That - For a single noun when it is far
(iii)These - For a plural noun when it is near
(iv)Those - For a plural noun when it is far

---

Distributive Pronouns - Pronouns that are used to show the distribution of a noun are called distributive pronouns
Example - None, any, some, each, every, either, neither, no one, everyone, everybody, nobody etc.

---

Reciprocal Pronouns - Pronouns that are made up of two different pronouns and show a mutual relationship are called reciprocal pronouns.
Example - Akash and Seema love each other
Indians love one another

---

Reflexive Pronouns - Pronouns that show the effect of work upon the subject are calle reflexive pronouns
Example - We enjoyed ourselves
She praised herself

---

Emphatic Pronouns - When reflexive pronouns are used for the purpose of emphasizing it becomes an emphatic pronoun. It is either used after the subject or in the mid of the sentence.
Example - I myself will go
You yourself can make way

---

Read More

One word substitution

1. A person who is above hundred years – Centenarian
2. A book published after the death of its author – Posthumous
3. A person whom we do not know – Anonymous
4. A cinema show which is held in the afternoon – Matinee
5. A citizen of the world – Cosmopolite
6. A contagious disease which spreads over a huge area – Epidemic
7. A Government by a king or a queen – Monarchy
8. A Government by one – Autocracy
9. A Government by the few – Oligarchy
10. A Government by the nobles – Aristocracy
11. A Government by the officials – Bureaucracy
12. A Government by the people – Democracy
13. A Government by the rich – Plutocracy
14. A handwriting that can’t be read – Illegible
15. A land animal that breeds in water – Amphibian
16. A life history written by oneself – Autobiography
17. A life history written by someone else – Biography
18. A list of books – Catalogue
19. A list of chapters at the beginning of a book – Index
20. A man devoid of kind feeling and sympathy – Callous
21. A man who has too much enthusiasm for his own religion – Fanatic
22. A man who is easily irritated – Irritable
23. A medicine that kills germs – Germicide
24. A medicine that prevents decomposing – Antiseptic
25. A medicine to counteract the effect of another medicine – Antidote
26. A person who does not believe in the institution of marriage – Misogamist
27. An unmarried woman - Spinster
28. An unmarried man - Bachelor
29. A person who hates women – Misogynist
30. A person who imports or exports goods into or from a country secretly because they are illegal – Smuggler
31. A person who knows everything – Omniscient
32. A state of perfect balance – Equilibrium
33. A statement which cannot be understood – Incomprehensible
34. A study of ancient things – Archaeology
35. A study of animals – Zoology
36. A study of birds – Ornithology
37. A study of men – Anthropology
38. A study of races – Ethnology
39. Misappropriation of money – Embezzlement
40. Murder of a one’s brother – Fratricide
41. Murder of a human being – Homicide
42. Murder of one’s father – Patricide
43. Murder of one’s mother – Matricide
44. Murder of an infant – Infanticide
45. Murder of self – Suicide
46. Murder of a King – Regicide
47. A man showing feminine attitude – Effeminate/Sissy
48. A person who can use both hands effectively – Ambidextrous
49. An animal feeding on grass and plants – Herbivorous
50. Animals living in flocks – Gregarious
51. Incapable of being tired – Indefatigable
52. One who always thinks himself to be ill – Valetudinarian
53. One who believes in fate – Fatalist
54. One who believes in God – Theist
55. One who does not believe in God – Atheist
56. Absence of Government – Anarchy
57. Animals that eat all kinds of food – Omnivorous
58. An animal that preys on other animals – Predator
59. An assembly of hearers at a lecture or a concert – Audience
60. An exact copy – Facsimile/Xerox
61. An office with salary but no work – Sinecure
62. One who does not care about art, literature, etc. – Philistine
63. One who does not make mistake – Infallible
64. One who does something not professionally but for pleasure – Amateur
65. One who doubts the existence of God – Agnostic
66. One who eats too much – Glutton
67. That which is prohibited by law – Illicit
68. That through which light partly pass – Translucent
69. That through which light cannot pass – Opaque
70. That which cannot be avoided – Inevitable
71. That which cannot be satisfied – Insatiable
72. That which is against law – Illegal
73. That which is lawful – Legal
74. That which is unlikely to happen – Improbable
75. The action of looking back on past time – Introspection
76. Water fit for drinking – Potable
77. Without life – Inanimate
78. Without payment – Gratis
79. Words which have the same meaning – Synonyms
80. Words which have the different meaning – Antonyms
81. Words written on the tomb of a person – Epitaph
82. Work for which no salary is paid – Honorary
83. Worship of idols – Idolatry
84. Incapable of being expressed – Inexpressible
85. Incapable of being conceived – Inconceivable
86. Incapable of being heard – Inaudible
87. Incapable of being conquered or overcome or defeated – Invincible/Unconquerable
88. Incapable of being seized – Impregnable
89. Incapable of being pierced or penetrated – Impenetrable
90. Incapable of being passed over or surmounted – Insurmountable/Insuperable
91. Incapable of being seen – Invisible
92. Incapable of being exhausted – Inexhaustible
93. Incapable of being defended – Indefensible
94. Incapable of being reached or approached – Inaccessible/Un-approachable
95. Incapable of being admitted – Inadmissible
96. Incapable of being admitted – Inadmissible
97. Incapable of being applied – Inapplicable
98. Incapable of being believed – Incredible/Unbelievable
99. Incapable of being altered – Unalterable
100. Incapable of being recovered – Irrecoverable
101. Incapable of being resisted – Irresistible
102. Incapable of being divided – Indivisible
103. Incapable of being disputed – Indisputable
104. Incapable of being reconciled – Irreconcilable
105. Incapable of being done – Impossible
106. Incapable of being questioned – Unquestionable
107. Incapable of being borne, or endured, or tolerated – Unbearable/Undurable/Intolerable
108. Incapable of being elected or chosen – Ineligible
109. Incapable of being corrected – Incorrigible
110. Incapable of being dissolved – Insoluble
111. Animals living on human flesh – Cannibals
112. One who is all-powerful – Omnipotent/Almighty
113. One who knows or sees everything – Omniscient
114. Liable to be easily kindled – Inflammable
115. Animals living on both land and water – Amphibian
116. animals that live predominantly or entirely on land - Terrestrial animals
117. animals that live predominantly trees - Arboreal animals
118. One who is present everywhere – Omnipresent
119. One looking at the bright side of things – Optimist
120. One looking at the dark side of things – Pessimist
121. A paper written by the hand – Manuscript
122. A speech delivered for the first time in an assemble – Maiden speech
123. A speech full of too many words – Verbose speech
124. A speech delivered without previous preparation – Extempore speech
125. The custom of having more than one wife – Polygyny
126. The custom of having more than one husband – Polyandry
127. The customer of having more than one spouse - Polygamy
128. A word which is no longer in use – Obsolete
129. One who speaks for others – Spokesman
130. One working in the same place – Colleague
131. One unable to pay one’s debt – Bankrupt/Insolvent
132. Beyond the power of nature – Supernatural
133. Destitute of knowledge – Ignorant
134. One who has the same name as another - Namesake
135. Speaking or writing many languages – Polyglot
136. One who knows many languages - Linguist
137. One who speaks less - Reticent
138. Doctor who treats ailment of eyes - Opthalmologist
139. Doctors who specializes in female treatment - Gynecologist
140. Doctor who specializes in teeth treatment - Dentist
141. Doctor who specializes in ear, nose, throat - ENT
142. Doctor who specializes in gums disease - Peridontist
143. Doctor who specializes in bone problems - Orthopedician
144. Doctor who specializes in heart problems - Cardiologist
145. Doctor who specializes in skin diseases - Dermatologist
146. Doctor who specializes in child treatment - Paediatric
147. Door partly open - Ajar

Read More

Adverbs - Class 7 Grammar

Adverb - An adverb is a word which generally qualifies or adds to the meaning of a verb, an adjective or another adverb

Kinds of adverbs

• Simple Adverbs
• Interrogative Adverbs
• Relative Adverbs
• Adverbs of Affirmation and Negation

---

Simple Adverbs - Simple adverbs are the adverbs that add to the meaning of a verb etc. in a simple manner. They tell time, place, manner, frequency, extent etc., the divisions of simple adverbs are mentioned below:

• Adverbs of Time tells when the action is indicated by its verb
  Example - tomorrow, soon, already, now, shortly etc.
• Adverbs of Place tells where the action is indicated by its verb
  Example - there, near, above, after, below, etc.
• Adverbs of Manner tells how the action is indicated by its verb.
  Example - well, loudly, carefully, gladly, quickly, etc.
• Adverbs of Frequency tells how often the action is indicated by its verb
  Example - seldom, often, twice, always, again, etc.
• Adverbs of Extent tells too what degree(extent) the action is indicated by its verb
  Example : very, too, quite, almost, hardly etc.

---

Interrogative Adverbs - An interrogative adverb is an adverb used to ask a question, some simple adverbs used as interrogative adverbs

When were you born?        (time)
Where were you born?        (place)
How do you go to school?      (manner)
How often do you travel?      (frequency)
How far is this news true?      (extent)

---

Relative Adverbs - Relative adverbs are adverbs which acts as a connection to join sentences together. Note: Interrogative and relative adverbs are same in form but they differ in position and function. Interrogative adverbs asks question directly whereas relative adverb uses the interrogative adverb but actually it is not used to ask something, some interrogative adverbs used as relative adverbs

I do not know when he will return.        (time)
Can you tell where he lives?       (place)
Do you know how to ride a bike?       (manner)
I know how often you have insulted him.       (frequency)
Tell me how far she is honest.       (extent)

---

Adverbs of Affirmation or Negation

Adverbs of Affirmation - An adverb that affirms a statement is called an adverb of affirmation
Adverbs of Negation - An adverb that negates a statement is called an adverb of negation

---

EXERCISES

Exercise 1. Spot the simple adverbs in each sentence, Tell its kind too:

1. The guests are standing outside. – Adverb of place
2. I shall being this work tomorrow. – Adverb of time
3. You cannot write Hindi well. – Adverb of manner or quality
4. I have already had my lunch. – Adverb of time
5. Send the peon here, please. – Adverb of place
6. I went there for you only. – Adverb of place
7. It is raining gently. – Adverb of manner
8. Will you repeat this sentence again? – Adverb of frequency
9. It is ratherhot Adverb of degree
10. I gladly accepted his offer. Adverb of manner
11. She is too tired to finish this work on time. Adverb of degree
12. My brother was taken ill yesterday. Adverb of time
13. Barking dogs seldombite Adverb of frequency
14. Have you seen such a silly fellow before? Adverb of time
15. The elephant stood inside the grove. Adverb of place
16. They have always helped the weak. Adverb of frequency
17. Anil is often late for school. Adverb of frequency
18. Do things slowly but surely? Adverb of manner
19. The man was nearlydegree Adverb of extent
20. Speak a little louder please. Adverb of degree
21. He left for Mumbai immediately. Adverb of time
22. I feel somewhat puzzled at it. Adverb of degree
23. Suddenly a bear appeared before us. Adverb of time
24. She seldom comes to see us. Adverb of frequency

Read More