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Health-
Physical and mental fitness is must for healthy mind of an individual. WHO has defined
health as state of complete physical, mental social well being and not merely the absence of
disease or infirmity.
A disease may occur due to following reasons: viruses, bacteria, fungi.

TYPES OF DISEASES:

▪ CONGENITAL DISEASES:
Diseases which are already present in the body since birth are called congenital
diseases.
Causes- genetic abnormality or when organ in the body is not fully developed.
Eg- colour blindness, haemophilia , thalassaemia.
Colour blindnessColour blindness is due to vision problem. This is because person lacks certain
pigments in eyes therefore it is called colour vision deficiency.
Most common colour blindness is red green colour deficiency.

Haemophilia: In this disease blood loses its ability to clot.

Thalassaemia: In this disease body makes haemoglobin and red blood cells lesser than normal
value.
It ultimately causes amaemia.

Acquired diseases:
Two categories- 1- communicable
2-Non communicable
1- Communicable or infectious diseasesDirectly or indirectly infection is paased from infected person to healty person.
Eg. Viruses ,bacteria.
2- Non communicable or non infectious diseasesDirectly or indirectly the diseases is spread from person to person or by
microorganisms.

COMMUNICABLE DISEASES :This diseases are classified on the basis of oraganisms that cause diseases.
Mode of spread- air, water, food from infectef persons
Diseases caused by bacteria

1- Tuberculosis-
• Causative organism- mycobacterium tuberculosis
• Incubation period: 2-10 weeks It is period between exposure to the
infection and appearance of first symptom
• Symptoms- Cough, sputum with blood, pain in chest, loss of
weight,etc
2- Cholera-
• Causative organism- vibrio cholera
• Incubation period- few hours to 5 days
• Symtoms- acute diaarhoea, vomiting dehydration, extreme thirst and
muscle cramp.
3- Typhoid-
• Causative organism- Salmonella thyphi
• Incubation period- 7-12 days
• Symptoms- high fever in afternoon, acute headache, reddish eruptin
on chest.
4- Leprosy-
• Causative organism- mycobacterium leprae
• Incubation period- several years
• Symptoms- loss of sensation, skin eruptions and deformation of skin
and toes.
5- Tetanus-
• Causative organism- clostridium tetani
• Incubation period- 4-20 days
• Symptoms- painful contraction of muscles, neck amd jaw followed by
paralysis.

Diseases caused by virusesCommon colddroplet infection spreads through moisture.
Incubation period- 1-3 days
Symptoms- running nose, headache , fatigue
InfluenzaDroplet infection
Upper respiratory tract infection
symptoms- fever, cold , chill, body ache
.
Measles Mode of transmission– direct contact through infected saliva and mucous
Symptoms- nasal discharge, redness of eyes and coughing.
ChickenpoxTransmission– contact with skin sores and clothes of patient
Incubation time- 14-16 days.
Symptoms– fever, head ache, small watery sores on skin
PolioAffects liver
Types- Hepatitis A,B,C,D,E,G,H

Causative organism- Human deficiency virus
Spread- sexual contact
Incubation period- 15 months- 5 years
Transmission- can transmit virus from mother to child
Precaution- Avoid sexual contact with infected person

DISEASE CAUSED BY PROTOZOA-
• AMOEBIASIS-
✓ caused by entamoeba histolytica
✓ Transmission- contaminated food and water
✓ Symptoms- diarrhoea, gripping pain, discharge of mucous
✓ Incubation period- one week
• Malaria-
✓ Caused by- Plasmodium
✓ Transmission- bite of female anopheles mosquit0
✓ Symptom- chillness, sever head ache, rising temperature
Diseases caused by worms

AIDS

1. Elephantiasis {Filaria}
   ▪ Causative organism- Wucheria bancrofti
   ▪ Spread-female culex mosquito
   ▪ Symptom- lympnodes in limbs, scotrum in males and breast in females.
2. Ascariasis-
   ▪ Occurs in small intestine
   ▪ Causation- Ascaris lumbricoides Spread- unsafe food and water
3. Taeniasis-
   ▪ Caused by tapeworm
   ▪ Symptom- pain, weight loss, digestive problems.
   TRANSMISSION OF COMMUNICABLE DISEASES
   Airborne diseases or droplet infectionBacteria, spores of fungi and viruses enter our body through inspiration and attack our
   throat, wind pipe and lungs.
   Microbes are present in saliva and blood
   When person sneezes in public places droplets are spread in air and transmitted to healthy
   person
   
   WATER BORNE AND FOOD BORNE DISEASES
   • Water is polluted in so many ways.
   • Dumping of sewage water in water bodies is cause of disease.
   • Uncleansed food contains bacteria and eggs of parasite; if not washed properly than
   diseases like diarrhoea and vomiting occur.
   • Botulism is serious food poisoning due to special bacterium.
   INSECT BORNE OR VECTOR BORNE
   o Organisms which carry disease containing pathogens to a healthy person without
   getting affected.
   o Contact diseases: spreads from one person to anothe directly or indirectly.
   o Unsanitary toilet habits should be avoided.
   Eg; conjunctivitis, chicken pox, common cold, etc.
   WAYS TO PREVENT COMMUNICABLE DISEASES
   o We should be very much careful regarding our personal cleanliness by taking a
   regular bath with good soap and shampoo.
   o Cove your nose and mouth with a tissue or handkerchief while coughing or sneezing.
   Do not forget to throw the tissue.
   o We should avoid using bathrooms and lavatories of railway station and cinema hall.
   o We should dustbins.
   o Food items exposed to flies should not be used.
   NON COMMUNICABLE DISEASES
   Nutritional deficiency diseases
   When all nutrients are done in right amount and ratio according to need its called balanced
   diet.
   A.PROTEIN ENERGY MALNUTRITION
   Deficiency of protein, fats and carbohydrates is called protein energy malnutrition.
   Eg- Kwashiorkor and marasmus
   Kwashiorkor- results due to diet poor in protein.
   Symptoms- protruding belly, mental retardation, bulging eyes, etc.
   
   Marasmus- Deficiency of proteins and carbohydrates.
   Child may suffer mental retardation.
   No change in skin colour and ribs look prominent and becomes thin.
   B. VITAMIN DEFICIENCY DISEASES
   Vitamins are vital though they are required in small quantities.
   1- Night blindness is caused by vitamin A
   2- Rickets are caused by vitamin D
   3- Haemolysis and sterility are caused by vitamin E.
   C. MINERAL DEFICIENCY DISEASES
   Metals and non-metals and their salts are called minerals.
   They do not supply energy to body.
   1- Muscle cramps is caused by deficiency of sodium
   2- Weakness of muscles or paralysis is caused by potassium
   3- Rickets is caused by deficiency of calcium
   DISEASES DUE TO MALFUNCTIONING OF ORGANISMS:
   • Diabetes mellitusIt is a hereditary disease
   When insulin secreted by pancreas is not in enough amounts than it can neither use the
   sugar nor store in liver in form of glycogen.
   Than sugar level becomes high. This is called diabetes mellitus.
   • Heart diseasesCoronary artery diseases and atherosclerosis are common.
   The blood vessels that supply blood to heart muscles are called coronary arteries. And
   arteries become hard its called atherosclerosis.
   The blood supply is reduced due to which heart muscles don’t get proper supply its called
   coronary artery disease.
   • Arthritis :It is joint disease.
   Found as two types – rheumatoid arthritis and osteoarthritis.
   
   • CANCER :It is characteristic by uncontrolled cell division.
   Malignancy refers to growing mass of cancerous cells. Renal disease or malfunctioning of
   kidney Due to some reason if kidney is malfunctioning and waste material accumulating in
   body is called uraemia. Due to head ache and extreme fatigue patient may go into coma.
   • ALLERGY :Unusual hypersensitivity of body tissues.
   Substances causing it are called allergens.
   • Asthma: Respiratory passage become swollen and constricted.
   Symptoms include coughing at night and shortness of breath, etc.
   BITES AND STINGS
   It needs immediate medical attention and is dangerous.
   Bite of snake may be dangerous and that of mosquito may be serious sometimes in case of
   carrier.
   BURNS AND FIRST AID
   First degree of burns is superficial burned
   Second degree of burns is called serious burns.
   Third degree of burn is called severe burns.
   CUTS AND THEIR FIRST AID
   If the cut is not deep is called superficial cut.
   If the cut is deep a cloth or pad should be kept on cut
   Bruises are injuries under the skin.
   Ways to prevent communicable diseases
   ❖ Diet and exercise play an important role
   ❖ Regular health screening and doctor check-up
   ❖ One should avoid fast food
   
   CLEANLINESS, HYGIENE, EXERCISE
   • Always eat clean and healthy food.
   • Always wash hands after and before meal
   • Never split in public places
   • Always cover your mouth and nose while sneezing.
   • Always take a balanced and healthy diet.
   BAD HABITS LEAD TO ILL HEALTH
   • Tobacco addiction- chewing of tobacco may lead to cancer of mouth
   • Drug addiction- symptoms like nausea, vomiting and pain in stomach may occur’
   • Addiction of fast food- they have dangerous effect on health
   • Alcohol consumption- it retards mental health and driving under influence of alcohol
   may cause accident
   • Unhealthy lifestyle- absence of physical activity and workout than unhealthy lifestyle
   increase the risk of heart ailments, blood pressure, and obesity and also makes us
   feel stressed

Map – A map is a representation or a drawing of the earth’s surface or a part of it drawn on a flat surface according to a scale.

Atlas – When many maps are put together we get an Atlas. Atlases are of various sizes, measurements drawn on different scales.

They are of different types of maps. Some of them are described below.

Physical Maps

Maps showing natural features of the earth such as mountains, plateaus, plains, rivers, oceans etc., are called physical or relief maps.

Political Maps

Maps showing cities, towns and villages, and different countries and states of the world with their boundaries are called political maps.

Thematic Maps

Some maps that focus on specific information; such as road maps, rainfall maps, maps showing distribution of forests, industries etc., are known as thematic maps.

There are three Components of Maps – distance, direction and symbol

Distance

Scale is the ratio between the actual distance on the ground and the distance shown on the map. Scale is very important on any map. If you know the scale, you will be able to calculate the distance between any two places on a map. When large areas like continents or countries are to be shown on paper, then we use a small scale. It is called a small scale map. When a small area like your village or town is to be shown on paper, then we use a large scale that is 5 cm. It is called a large scale map.

Direction

There are four major directions, North, South, East and West. They are called cardinal points. Other four intermediate directions are north-east (NE), southeast (SE), south-west (SW) and north-west (NW). We can find out the direction of a place with the help of a compass. It is an instrument used to find out main directions. Its magnetic needle always points towards north-south direction.

Symbols

It is the third important component of a map. It is not possible to draw on a map the actual shape and size of different features such as buildings, roads, etc. So, they are shown by using certain letters, shades, colours, pictures and lines. These symbols give a lot of information in a limited space. Maps have a universal language that can be understood by all. There is an international agreement regarding the use of these symbols. These are called conventional symbols.

Various colours are used for the same purpose. For example, generally blue is used for showing water bodies, brown for mountain, yellow for plateau and green is used for plains.

Sketch

A sketch is a drawing mainly based on memory and spot observation and not to scale. Sometimes a rough drawing is required of an area to tell where a particular place is located with respect to other places. Such a rough drawing is drawn without scale and is called a sketch map.

Plan

A plan is a drawing of a small area on a large scale. A large-scale map gives a lot of information, but there are certain things, which we may sometimes want to know, for example the length and breadth of a room, which can’t be shown in a map. At that time, we can refer drawings drawn to scale called a plan

Mountains

• A mountain is any natural elevation of the earth surface.
• There are permanently frozen rivers of ice. They are called glaciers.
• Mountains may be arranged in a line known as the range.
• The Himalaya, the Alps and the Andes are mountain ranges.
• There are three types of mountains—Fold Mountains, Block Mountains and Volcanic Mountains.
• The Himalayan Mountains and the Alps are young fold mountains.
• The Aravalli range in India is one of the oldest fold mountain systems.
• Block Mountains are created when large areas are broken and displaced vertically.
• Volcanic mountains are formed due to volcanic activity, e.g. Mt. Kilimanjaro in Africa

Plateaus

• A plateau is an elevated flat land.
• The Deccan plateau in India is one of the oldest plateaus.
• The Tibet plateau is the highest plateau in the world.
• The African plateau is famous for gold and diamond mining.
• The lava plateaus are rich in black soil that are fertile and good for cultivation.

Plains

• Plains are large stretches of flat land.
• Most of the plains are formed by rivers and their tributaries.
• In India, the Indo-Gangetic plains are the most densely populated region of the country

Landforms and the People

• Humans have been living in different kinds of landforms in different ways.
• Sometimes, natural calamities such as earthquakes, volcanic eruptions, storms and floods cause widespread destruction.

The surface of the earth is not the same everywhere.

Mountains, plateaus and plains are different landforms of the earth.

A mountain is a natural elevation of the earth surface. There are three types of mountains—Fold mountains, Block mountains and Volcanic mountains.

A plateau is an elevated flat land. It is a flat-topped table land standing above the surrounding area. A plateau may have one or more sides with steep slopes.

The Deccan plateau is one of the oldest plateaus.

The Tibet plateau is the highest plateau in the world.

Plains are large stretches of flat land. Some plains are extremely level while others may be slightly rolling and undulating

Plains are generally thickly populated regions of the world

Human habitation is found on different kinds of landforms. But population varies on these landforms. Mountains are generally not thickly populated. But plains are the regions where the thick population is found.

The land is precious. We must not use it in a wasteful manner. Construction work of any type should not be carried on fertile land. Also, we should not throw garbage on land. It is our duty to take care of the land or any other natural gift. If we do this we will be conscious citizens.

Erosion: The wearing away of the earth’s surface is known as erosion.

Mountain: A mountain is a natural elevation of the earth surface.

Glacier: Some mountains have permanently frozen river of ice. They are called glaciers.

Range: When mountains are in an arranged line, it is called a range.

Horsts and graben: The uplifted blocks are known as horsts and the lowered blocks are known as graben.

Storehouse: A building where things are stored or kept.

Terraces: One of the series of flat areas of ground which are cut into the side of a hill like steps in order to grow crops there.

Flora: The plants of a particular area.

Fauna: The animals living in an area.

Plateau: A plateau is an elevated flat land. It is a flat-topped table land standing above the surrounding area.

Plain: A plain is a vast stretch of flat land where the thick population is found.

1.            The Aryans were nomadic people who came to India from the north-west.

2.            They settled down and gradually took to agriculture.

3.            Our knowledge of the Aryans comes from the Vedas.

4.            The Rigveda gives information about the Early Vedic Age.

5.            The period when the Aryans first settled in India is known as the Early Vedic Age (1500 BCE to 1000 BCE).

6.            During this period, the kingdoms were tribal in character.

7.            The period between 1000 BCE to 600 BCE is known as the Later Vedic Age.

8.            The king now became very powerful and the status of women declined.

9.            Megalithic burials have been found in many places in India.

10.          Inamgoan is believed to have been occupied from 1600 BCE to 700 BCE.

Have you ever heard or recited the Gayatri Mantra? It is from the oldest text in India called the Rigveda. There are four Vedas. The Rigveda is the oldest among them. The Vedic Age is the period during which the Vedas were composed. This period from 1500 BCE to 600 BCE, is often called the Vedic Age.

Earlier, we have read about the Harappan Civilisation. Slowly it declined and by around 1800 BCE, people again began living a simple life in villages. About this time, some people entered India from the north-west. They called themselves ‘Arya’ meaning ‘noble ones’. A new culture developed in India with the arrival of the Aryans. They did not come to India to invade and plunder and go back. They settled down in the plains and took to agriculture. They first settled in seven places in the Punjab region which they called Sapta Sindhu. These Aryans who settled in India are called Indo-Aryans.

STUDY OF VEDAS    

Our knowledge of the Aryans comes from the Vedas. The Vedic Age gets its name from the four Vedas. Historians have studied these texts carefully. They provide an insight into the life of the Vedic Age.

LANGUAGES

The Aryans spoke a language called Indo- European which was the ancestor of Sanskrit, Assamese, Gujarati, Kashmiri and many other foreign languages like Latin, Greek, German and Persian. Similar words exist in all these languages. In India, the languages used in the north-east belong to the Tibeto-Burman family. Tamil, Telugu and other languages of the sout belong to the Dravidian family.

The oldest Veda is the Rigveda. It was composed about 1500 BCE and is a collection of 1028 hymns written by rishis. These hymns are in praise of various gods and goddesses. These hymns were considered sacred. For hundreds of years, the Rigveda was passed down by word of mouth. Finally, it was written down in Sanskrit. The other three Vedas were written later and tell us about the Later Vedic Age.

EARLY VEDIC AGE

The period when the Aryans first entered India is known as the Early Vedic Age (1500 BCE to 1000 BCE). The chief source of information about this period is the Rigveda.

Political Organisation

The kingdom was tribal in character. The tribal chief was called rajan. He ruled over the people (jana) and not over any specific area of land. His position was not hereditary. He did not live in any palace and did not collect regular taxes. His main function was to protect the people and lead the army to victory in battle. Battles were fought for land which was essential for agriculture and for pastures for the cattle. He used to receive a large part of the booty collected in battle. He was also called gopati (Lord of Cattle) indicating that protecting and increasing the cattle was his other major role. He received from the people a voluntary offering called ball. The king did not maintain a standing army. The king’s power as kept in check by assemblies such as sabha and samiti. The king dispensed his duties with the help of the purohita (religious advisor) and senani (army chief).

Q. Why was the king called gopati? Why were cattle so important?

Status of Women

Women were treated equally and were allowed some choice in the selection of their husbands. They received education also. Child marriage and sati1 did not exist and widows were not treated badly. Women participated in the sabha, rituals and even chariot races.

History Reveals

The Rigveda has many hymns composed by women and there are references to women sages.

Economic life

The Aryans did not have any fixed territories and they moved from place to place with their cattle and horses. As they began to settle down, they began to practice agriculture. Cattle were the most-valued possession and chief form of wealth. Besides agriculture and cattle rearing, there were many other professions. People were also engaged in trade.

History Reveals

Ships were also used by the Early Vedic people. The Rigveda speaks of ‘?ships with a hundred oars?.

Religion

People worshipped the forces of nature. Much of the Rigveda is full of prayers for these deities. The important gods were Indra, Varun, Surya, Vishnu, Vayu and Yama. Some goddesses were Usha, Savitri and Prithvi. Their favour could be won by sacrifices. They did not make temples or idols. They worshipped through prayers and chanting Vedic mantras.

LATER VEDIC AGE

The period between 1000-600 BCE is known as the Later Vedic Age. We know about this age through the books that were composed during this period.

Samaveda: It is a collection of musical verses from the Rigveda.

Yajurveda: This contains mantras and rituals for sacrifice.

Atharvaveda: This contains chants to cure diseases and ward off danger.  The epics, Mahabharata and Ramayana, were also written during this age. They tell us about the political and social setup of that period and are considered religious texts. This age is also called the Epic Age because these two great epics were written during this period.

Political Organisation

Each tribe now occupied a fixed territory which as named after the tribe. Tribes often fought over territories. The term rashtra which indicates territory first appeared in this period. The king became very powerful and his position became hereditary. He lived a luxurious life in a palace. He received regular taxes in the form of food grains or cattle. He appointed officers to collect taxes. He maintained law and order and all major decisions were taken by him. The sabha and samiti assisted him but did not curtail his power. He performed various sacrifices to prove his strength and power.

Status of Women

There was a drastic change in the position of women. They were not educated or allowed to read the Vedas. They no longer participated in the sabha. Child marriage and sati came into existence and widow remarriage was strongly opposed. The women were supposed to be under the control of her father and later her husband.

Caste System

The caste system developed gradually. The Aryans made the defeated dasas do unpleasant work. Division was created between the dasas and the fair-skinned Aryans. The dasas were given the name shudras and were not allowed to take part in any Aryan ceremony. Hence the caste system consisting of the four castes came into being-the brahmins, kshatriyas, vaishyas and the shudras. We will be learning more about the caste system in the later chapters.

Economic life

Agriculture became very important. Copper, bronze and iron implements were used. The main crops were wheat, rice and barley. Artisans2 produced better goods. Weaving was practiced on a wide scale mostly by women.

Religion

New gods were worshipped. Prajapati, the creator, was most important. He was later called Brahma. Shiva and Vishnu were also worshipped. Idol worship also began. Sacrifices were performed to please the gods who then blessed the people.

Thus, the Aryans brought with them their customs and ways of thinking and influenced the lives of the natives.

MEGALITHS

The word megalith comes from the Greek words megas and lithos meaning ‘great stone”. Megaliths are large slabs of stone used to mark the burial sites. Numerous megaliths have been found in Karnataka, Andhra Pradesh, Maharashtra, Kerala, Kashmir and the north- east.

In a megalithic burial, the bones of a dead person were placed in an urn. This urn was buried and surrounded by a circle of large vertical stones. A large horizontal stone formed the capstone.

If the pit burial has a circle of large stones, it is called a pit circle. If the pit had a heap of stones piled on top, it is called a cairn.

Unlike the Neolithic burials which were in the habitation area, megalithic burials were away from the occupation area. Grave goods like pottery, ornaments and weapons were also found. Pottery was of black and red variety. Weapons consisted of iron axes, spades and daggers. Ornaments were made of carnelian and gold. Some copper objects were also put in the grave. Sometimes horse skeletons and equipment were also found. The number of grave goods probably depended on the status of the person. The presence of these goods is indicative of their belief in afterlife. Some graves have skeletons of more than one person. This is suggestive that probably people from the same family were buried in the same place. The people who died later were got in through portholes.

Megaliths were built with great care and must have been an important part of the lives and beliefs of the people who constructed them.

INAMGAON          

Inamgaon is a village in Pune district of Maharashtra. It is located near the River Ghod, a tributary of River Bhima. It is said to have been occupied from 1600 BCE to 700 BCE.

Houses here had fire pits. The pottery was fine, well-baked and designed. A pottery kiln has also been identified. There was an increase in farming and animal domestication. They cultivated grams, beans, peas and lentils apart from wheat, barley and rice. Fruits like berries and dates were also collected.

Bones of animals have been found. These bones have cut marks which are evidence that animals were also used for food.

The adult dead bodies were mostly buried away from the abitation site. Sometimes the burials were in the houses. The dead body was laid out straight, with the head towards the north. A number of burial goods including pots, ornaments and tools were also buried with the dead person. Multiple burials have also been found. In some graves, more than one skeleton and the absence of burial goods indicate that there was probably a large scale killing because of which burial goods were not enough for all the graves. In one large house which had a granary, one man was found buried in a cross legged position in a clay jar.

Q. Why do you think Inamgaon was located near a river?

Around the World

During the Shang Dynasty (1600-1046 BCE) in China, seers4 used bones or shells of tortoises for reading oracles5. They inscribed a question which they wanted to ask on the oracle bone. The bone was then heated. The cracks formed in the bone were studied and interpreted. Archaeologists have found thousands of oracle bones and shells in China. Oracle bones of the Shang Dynasty were ox scapulae and plastrons6 only. They had characters and holes drilled into them.

Palaeolithic: This term refers to the age where we find a large number of stone tools. It extends from 2 million years ago to about 12,000 years ago and is divided into Lower, Middle and Upper Palaeolithic.

Mesolithic: This period extends from 10,000 years ago to about 12,000 years ago. Stone tools found during this period were generally tiny and were called Microliths.

Neolithic: This was the period that dates back to about 10,000 years ago, and is, therefore, known as the New Stone Age.

The Earliest People: They were hunter-gatherers, a name derived from the way they collected food. They hunted animals, collected berries and fruits and gathered nuts, stalks and eggs. To hunt, they needed to move constantly, and to gather plant products, they needed knowledge about the edibility of plants and change of seasons.

Archaeological Evidence of Early Man: How do we know about the early man? This has been possible through an analysis of objects found, which were probably used by the early man. For example, tools made of stones, bones and wood.

Uses of Tools: Stone tools were used to cut meat and bones, scrape bark (from trees) and hides (animal skins) as well as to chop fruit and roots.

Making Stone Tools: Two different techniques were used for making stone tools.

Choosing a Place to Live In: Dwellings chosen by the early man were located near sources of water, such as rivers and lakes as well as where the good quality stone was available for their tools.

Painting-Rock paintings: Paintings on a rock shelter.

Finding out about Fire: At Kurnool caves in Andhra Pradesh, evidence and traces of ash have been found suggesting use of fire. The fire might have been used as a source of light, to cook meat and to scare away animals.

A Changing Environment: About 12,000 years ago, there was a major change in the climate of the world. This change led to a shift to warm conditions, leading to the development of grasslands at many places which helped people to start thinking about the herding and rearing animals.

Habitation-cum-Factory Sites: Places where stones were found and early people made their tools. Sometimes, people lived (habitat) here for a longer span of time.

Bhimbetka: This is a place in Madhya Pradesh where we find examples of habitation sites, natural caves and rock shelters.

People who lived in the subcontinent about 2 million years ago were Hunter-gatherers. They hunted wild animals and gathered plant produce to get their food. They moved from place to place, in search of more food, water and resources.

Hunter-gatherers made and used various types of tools—tools of stone, wood and bone

Habitation refers to the place where people lived.

Stone tools were made using different techniques like a stone on stone (using a stone to give required shape to another stone) and pressure flaking.

The fire was used by the early people. They used fire as a source of light, to cook meat and to scare away animals.

Grasslands developed in many areas due to change in climate around 12000 years ago. Herding, and rearing animals and fishing became common.

Several grain-bearing panes of grass, like wheat, barley, rice grew naturally in different parts of the subcontinent. The people also began growing plants on their own.

Many old caves have paintings on their walls. They show wild animals and are drawn with great accuracy and skill. A painting from a rock shelter.

In Hunsgi, a number of early Palaeolithic sites have been found. A large number of tools were also found, most of which were made of limestone.

Factory-Sites: Places where the stone was found and where people made tools are called Factory-sites.

Grasslands: Areas of land with high fertility and thus good for growing crops are called Grasslands.

Habitation-Cum-Factory Sites: Factory-sites, where people lived for some time, have been called Habitation-cum-factory sites.

Hunter-Gatherers: People who lived in the subcontinent about two million years ago and who hunted wild animals, caught fish and birds, gathered food to eat, were the Hunter-gatherers.

Palaeolithic: The part of history extending from 2 million years ago to about 12,000 years ago is called the Palaeolithic period.

Mesolithic: The part of history extending from about 12,000 years ago to about 10,000 years ago is called the Mesolithic period.

Microliths: Stone tools of the Mesolithic period are called Microliths.

Dateline:

What can we know about the past?

There are several things we can know about our past such as:

1. What people used to eat, the type of clothes they used to wear, the houses in which they lived.
2. How were the lives of hunters, herders, farmers, rulers, merchants, priests, crafts persons, artists, musicians, and scientists?
3. The games children used to play, the stories they have heard, the songs they sang.

Where did people live?

People have lived along the banks of the Narmada river for several hundred thousand years. These people stayed on the bank of Narmada river as they knew about the vast wealth of plants in the surrounding forests. They used to collect roots, fruits and other forest produce for their food. Sometimes they also hunted animals.

1. The areas where women and men first began to grow crops such as wheat and barley was about 8000 years ago.
2. People also began to look after animals like sheep, goat, and cattle and used to live in villages.
3. The places where rice was first grown are to the north of the Vindhyas.
4. About 2500 years ago, cities developed on the banks of the Ganga and its tributaries, and along the sea coasts.

In ancient times, the area along the Ganga and its tributary rivers, to the south of the Ganga was known as Magadha which is now lying in the state of Bihar. Men and women moved in search of livelihood and also to escape from natural disasters like floods or droughts. These movements of people enriched our cultural traditions. People have shared new ways of carving stone, composing music, and even cooking food over several hundreds of years.

Names of the land

Our country is known by both words i.e India and Bharat.

1. The word India comes from the Indus, called Sindhu in Sanskrit. The Iranians and the Greeks who came through the northwest about 2500 years ago called it the Hindos or the Indos, and the land to the east of the river was called India.
2. The name Bharata was used for a group of people who lived in the northwest, and who are mentioned in the Rigveda, the earliest composition in Sanskrit (dated to about 3500 years ago). Later it was used for the country.

Finding out about the past

One way through which we can find out about our past is by reading the books that were written long ago. These books are called manuscripts because they were written by hand. These were written on palm leaves, or on the specially prepared bark of a tree known as the birch, which grows in the Himalayas. These books dealt with all kinds of subjects: religious beliefs and practices, the lives of kings, medicine and science. Besides, there were epics, poems, plays as well.

Inscriptions

Inscriptions are writings on relatively hard surfaces such as stone or metal. In the past, when kings wanted their orders inscribed so that people could see, read and obey them, they used inscriptions for this purpose. There are other kinds of inscriptions as well, where men and women (including kings and queens) recorded what they did. For example, records of victories in battle.

Archaeologists

An archaeologist is a person who studies the remains of buildings made of stone and brick, paintings and sculpture. They also explore and excavate to find tools, weapons, pots, pans, ornaments and coins. They also look for bones of animals, birds, and fish to find out what people ate in the past.

Historians use the word source to refer to the information found from manuscripts, inscriptions and archaeology. Once sources are found, learning about the past becomes an adventure. So historians and archaeologists are like detectives, who use all these sources like clues to find out about our pasts.

One past or many?

The title of this book is Our Pasts – I. The word ‘pasts’ in plural is used to draw attention to the fact that the past was different for different groups of people. For example, the lives of herders or farmers were different from those of kings and queens, the lives of merchants were different from those of crafts persons, and so on. It is even true today as people followed different practices and customs in different parts of the country.

Archaeology did not help us to know more about the ordinary people in the past because they did not keep records of what they did. Whereas, kings used to keep the records of their victories and the battles they fought.

What do dates mean?

The years are counted from the date to the birth of Jesus Christ, the founder of Christianity. All dates before the birth of Christ are counted backwards and usually have the letters BC (Before Christ) added on. In this book, we will refer to dates going back from the present, using 2000 as our starting point. 2000 means 2000 years after the birth of Christ.

The name atom comes from the Greek word ‘atomos’, which means uncuttable or indivisible.

An atom is the smallest particle of an element having the same chemical properties of the element. Atoms are the basis for everything in the universe, including us.

Atoms are tiny particles that are too small to see, even with a microscope. They are so tiny that if people were the same size as atoms, the entire population of the world would fit into a small box.

Just like letters are the basic building blocks of any language, atoms are the primary building blocks for things around us. The chair you sit on, the lunch box you carry to school, pizza you eat  – just everything is made up of atoms.

When atoms combine together they form molecules.

Let us study about the atoms and molecules in detail. 

 Dalton’s Atomic Theory:

• Matter is made of atoms which cannot be broken down further.
• Atoms cannot be created or destroyed in a chemical reaction.
• Atoms of the same element are identical to each other while atoms of different elements differ in mass and chemical properties.
• Atoms combine in definite ratios of whole numbers to form compounds.
• The number and composition of atoms are constant for a given compound.

A few important definitions

1. Atom: Atom is the smallest unit of matter and is further made up of protons, neutrons, and electrons. Atomic radius is measured in nanometres (10−910−9 m)
2. Atomic mass: A mass unit equal exactly to 112th112th the mass of one atom of Carbon-12
3. Gram atomic mass: The atomic mass of an element expressed in grams is called gram atomic mass
4. Molecule: The smallest unit of an element or a compound which can exist independently and show all its physical and chemical properties is called molecule. A molecule may have atoms of the same kind(element) or of different kinds (compound)

We come across many chemical substances and compounds daily. Everything around us consists of chemical substances. These may be man-made chemical substances and substances extracted from nature

Examples of chemical products at home are dishwashing and cleaning detergents, glue, common salt, baking soda, etc

 These chemicals are made up of atoms of a fixed proportion and these atoms are arranged in a certain way. In order to find out what these proportions are and how they are arranged for any given substance, we need to know the chemical formula of the substance or compound.

In order to make it easier to describe elements and molecules, chemical formulae are used. They are used to describe the number of atoms in each element or compound. It contains the symbols of the atoms of the elements present in the compound, as well as how many there are for each element in the form of subscripts.

For example, ‘H’ represents one atom of hydrogen and ‘O’ represents one atom of oxygen.  If we want to represent two atoms of hydrogen, instead of writing H H, we write H₂. The subscript “2” means that two atoms of the element hydrogen have joined together to form a molecule.

We will study about the formulae in this chapter.

Importance of chemical formulae:

• It tells us about the types of elements present in the compound
• It tells us the number of atoms of each kind present in the molecule of the compound
• It gives us the mass of one molecule of the compound

 Chemical Formulae

• Every chemical substance is known by a specific name.
• Each chemical compound is represented by a chemical formula that gives its composition (constituent elements present) and the number of elements of each type present. 

Molecular Formula

• A chemical formula that represents the composition of a molecule of the substance in terms of the symbols of the elements present in the molecule is also called molecular formula.
• For example, the molecular formula of water is H₂O, which means that one molecule of water contains two atoms of hydrogen and one atom of oxygen.

Significance of Molecular Formula

• It represents name of the substance
• It represents one molecule of substance
• It gives the names of all the elements present in one molecule of the substance. It also gives the number of atoms of each element present.
• It represents a definite mass and refers to the presence of 6.023 x 10²³ molecules (known as the mole concept).

Ancient people like the Greeks, Romans, Indians, the Chinese, knew about elements like iron, copper, gold, silver, lead etc. The first element humans knew was most probably the carbon, in the form of charcoal.

There are about 115 elements out of which there are 92 elements that occur naturally. Most of them were discovered by the late 1800’s.

 The modern arrangement of the elements is known as the Periodic Table of Elements and is arranged according to the atomic number of elements. The scientist Dmitri Mendeleev, a Russian chemist, proposed an arrangement of know elements based on their atomic mass.

• The periodic table of the chemical elements is a tabular display of the known chemical elements. Each element is listed by its atomic number and chemical symbol.
• Symbols are used to represent elements. A symbol is a letter or picture used to represent something. One or two letters are used to represent elements. Example: The symbol for aluminum is Al and the symbol for oxygen is O.
•  A chemical formula is used as a quick way to show the composition of compounds. Letters, numbers, and symbols are used to represent elements and the number of elements in each compound.

Let us study in detail about elements, compounds, symbols, and formulae in this chapter.

Substances

 Substances:

Substances are classified into two types.

• Pure Substances – A substance which is made of one kind of particle.

Examples – iron, gold

• Impure substances or Mixtures – A substance which contains two or more different particles is known as a mixture.

Example: a salt solution is made up of two components, salt, and water.

On the basis of their chemical composition, pure substances are classified as elements and compounds.

Elements :

A pure substance which is made up of only one kind of atom and cannot be broken into two or more simpler substances by physical or chemical means is referred to as an element. Example: Zinc, Sulphur.
 

Characteristics of elements:

• An element is homogeneous in nature; it is a pure substance, made up of only one kind of atoms. For example, iron and silver are made of only iron and silver atoms.
• An element cannot be broken down into simpler substances by any physical or chemical methods such as heat, light electricity, or chemical reactions with other substances. For example, if you were to smash a piece of iron into smaller pieces or heat it, the piece still remains as the element iron.
• An atom is the smallest unit that shows all the properties of an element. For example, an atom of iron shows all the properties of that metal.
• Elements have sharp melting and boiling points.

Symbols to represent elements:

Each element is represented by a symbol. It is usually derived from the first letter of its name in English or Latin. The first letter of the symbol is always in upper case. Some elements are represented by the starting alphabet of its name. Example: Carbon is represented as C. Symbols of some elements are the first two alphabets, where the second alphabet is in the lower case. Example: Sodium is represented as Na, where Natrium is the Latin name of sodium.

Compounds:

• They are made up of one or more elements and are denoted by chemical formulae.
• A compound contains atoms of different elements chemically combined in a fixed ratio.The smallest unit of a compound is a molecule
• Compounds contain different elements in a fixed ratio arranged in a defined manner through chemical bonds.
• A compound can be broken down into simpler substances by chemical methods/reactions 
• A compound is represented using a formula. Example: Water (H₂O), Sodium chloride (NaCl),Magnesium oxide (MgO)

Water is one of the essential element for life on earth. Most of the earth’s surface is covered with water. Any guesses on how much fraction of the earth is covered with water?

About three-fourth of earth’s surface is covered with water.

An interesting fact for you to know is that most part of the human body consists of water.

We need water in daily life for different purposes: drinking, washing clothes and utensils, cooking, watering plants to name a few. As already stated most of the earth’s surface contains water, yet all of it can not be utilised. So how and from where do we get water for daily use?

In this chapter, you will learn about sources of water, different states of water, water cycle, the importance of water, water-borne diseases, and finally purification of water.

Sources of water

• Most of the earth’s surface is covered by the oceans.
• Sea is the largest source of natural water, but it contains a high amount of dissolved salt and cannot be used directly for irrigation or drinking.
• Rivers and lakes contain water that comes from glaciers or rainfall. As rivers flow downhill and through plains, they collect many substances like minerals, organic matter, clay. Sometimes bacteria may also be present in river water.
• We meet all our domestic and industrial requirements of water from rivers.
• Ground water is a pure form of water because it has no suspended impurities or germs. However, it may have dissolved minerals which give it a distinct taste and even medicinal properties.
• We can obtain ground water by digging wells.
• Rainwater is the purest form of water.
• It will contain dissolved substances like dust, carbon dioxide, oxygen and nitrogen.

States of water

• Water exists in all three states of matter: solid, liquid and gas.
• Ice, water and steam have different physical properties but same chemical properties.
• The interconversion of these three states of water also occurs in nature and it is called the water cycle.

Water cycle

Evaporation:

Heat from the Sun causes water on Earth (in oceans, lakes etc.) to evaporate (turn from the liquid into the gas) and rise into the sky. This water vapour collects in the sky in the form of clouds.

Condensation:

As water vapour in the clouds cools down it becomes water again, this process is called condensation.

Precipitation:

Water falls from the sky in the form of rain, snow, hail, or sleet, this process is called precipitation.

Collection:

Oceans and lakes collect water that has fallen. Water evaporates into the sky again and the cycle continues.

Importance of water

Commercial water use includes fresh water for motels, hotels, restaurants, office buildings, other commercial facilities, and civilian and military institutions. Domestic water use is probably the most important daily use of water for most people.

Domestic use includes water that is used in the home every day, including water for normal household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens.

Industrial water use is a valuable resource to the nation's industries for such purposes as processing, cleaning, transportation, dilution, and cooling in manufacturing facilities. Major water-using industries include steel, chemical, paper, and petroleum refining. Industries often reuse the same water over and over for more than one purpose.

Irrigation water use is water artificially applied to farm, orchard, pasture, and horticultural crops, as well as water used to irrigate pastures, for frost and freeze protection, chemical application, crop cooling, harvesting, and for the leaching of salts from the crop root zone.

Nonagricultural activities include self-supplied water to irrigate public and private golf courses, parks.

Potable water:

Potable water is required for human consumption (drinking). It must be:

• Clean and transparent.
• Free of germs and suspended impurities.
• It should contain some amount of gases and minerals so that it does not taste flat.
• It should not have harmful chemicals.

Waterborne diseases

Drinking dirty or contaminated water causes water borne diseases.

Some waterborne diseases are:

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Purification of water

Water must be treated or purified to make it fit for human consumption.

Coagulation stage: 

• Alum and other chemicals are added to the water at this stage.
• Suspended particles get stuck to the chemicals to form &#39;floc&#39;.

Sedimentation Stage:

• As particles get stuck they become heavy and sink to the bottom of the chamber.
• At this stage, most of the particles are stuck to form sediments, sinking to the bottom.
• The water is passed onto the Filtration chamber.

Filtration stage:

• As water passes slowly through this chamber, finer particles (sediments) are filtered out over layers of sand, charcoal and gravel.

Disinfection stage:

• Chlorination or addition of chlorine to water is used to kill any bacteria and other living organisms that may be in the water.
• It is very normal and natural for fresh water to contain living organisms.

Ozonization:

• Because of its excellent disinfection and oxidation qualities, ozone is widely used for drinking water treatment.
• Ozone can be added at several points throughout the treatment system,

Storage stage:

• The water is then passed into large storage tanks and left for a while for the action of disinfection to be complete.
• At the tail end of this storage tanks, huge pipes are connected to transport water to our homes and workplaces.
• At home, the easiest way to sterilise water is by boiling. Boiling water kills germs and makes it safe for drinking.
• Filtering through a cloth also removes soil and other large particles.
• Chlorine can be added to overhead tanks to disinfect water.
• Apart from this, we can also install RO systems or water purifiers with activated carbon filters to purify water.

Any liquid in which a solid dissolves easily is known as a solvent. Water has this excellent property of dissolving many substances.

Can you name one or two substances which you use every day, which easily dissolves in water?

They are the salt and the sugar.

Similarly, there are many other substances which dissolve in water. Hence, the name universal solvent for the water. In this chapter, you will learn more about water as a solvent and you will also learn step-by-step procedure to prove that tap water and sea water contain dissolved solids and gases.

1. Water has the ability to dissolve many substances in it. However, water dissolves different amounts of different substances under the same conditions. For e.g., for the same volume of water, we can dissolve more sugar than salt.
2.  Aquatic life depends on the oxygen dissolved in water.
3. Stirring and heating increase solubility of a substance.
4. Pure water is transparent, colourless, tasteless and odourless.

Temperature and solubility:

• Add a 1/2 cup of lukewarm tap water to a plastic cup.
• Weigh about 5 tablespoons of salt and gradually add the salt to the tap water, stirring to mix.
• Stop adding salt when it no longer dissolves.
• Repeat the mixing steps with 1/2 cup each of ice water and hot water; determine at which temperature more salt dissolves.
• This experiment proves that the solubility of some substances is dependent on temperature, and we observe that much more salt dissolves in hot water than in cold.

Experiment to show that tap water and sea water contain dissolved solids and gases

1. Two round bottom flasks are filled with tap water and sea water respectively and heated. Bubbles of gas will be released from the water and travel into the test-tube. Continue until the contents of the flask are boiling.
2. About half a test-tube full of gas will be collected in each case, all of which has been displaced from solution by heating.
3. A glowing splint continues to glow and does not immediately go out when placed in the gas.

If both samples of water are placed in an evaporating dish and allowed to evaporate, the water completely evaporates leaving behind traces of solids in the dish, showing that the samples of water contain dissolved solids.

Water plays a very important role for all of us in daily lives. You might postpone eating food, but you definitely need water to quench your thirst. Even though most of the earth’s surface is covered with water, most of it is unusable. 

Have you tasted sea water?

In case you have, it is very salty, right?

So, one of the main sources of water is rain. Rainwater is collected in rivers, tanks, reservoirs which are available for use by all living beings. It is essential to conserve water and make sure that the water is not polluted by industrial waste or any such means, water is not wasted and so on. It is the responsibility of all of us to preserve and conserve water for generations to come. In this chapter, you will learn about the importance of water, water conservation, water pollution and preventing water pollution.

• Water is a precious natural resource and we must conserve water.
• We can conserve water by using it in a wise manner.
• 97% of all the water on the earth is salt water, which is not suitable for drinking. Only 3% of all the water is fresh water, and only 1% is available for drinking. That is why we must conserve water.

A few simple ways to reduce usage and wastage of water:

• Turn off the tap when you brush your teeth.
• Fix a dripping tap and leaking pipes.
• Use a bucket instead of the shower.
• Water your garden with a watering can rather than a hosepipe.
• Rainwater harvesting is used by many people to save and use rainwater.
• Use drip irrigation on fields.
• Grow more trees to maintain water cycle.
• Avoid water pollution.
• Build dams to store and conserve water.

Water pollution:

• Sewage, kitchen and industrial wastes are dumped into the water.
• Chemicals from farms (dissolved fertilisers) and acidic waters from mines and industries pollute the water.
• Nuclear and thermal power plants use water for cooling purposes and discharge the hot water into seas and rivers. This causes an increase in temperature of the water and kills fish and plants in the water.

Water pollution can be controlled by:

• Treatment of sewage before being released into rivers.
• Removal of solid waste and garbage from sewage.
• Avoid using detergents, fertilisers, plastics and pesticides which can increase the chemical content of the water.
• Treat all effluents from factories to make them harmless.
• Avoid using lakes, ponds and rivers for bathing, washing animals and defecating and for disposing of dead bodies.

Anything which occupies space and has mass is called “Matter”.
Eg. Oxygen, air, silver, steel

Characteristics of matter:
Things around us are composed of different kinds of materials. In the same material same
type of molecules are found such as in case of ice, water molecules are present.
(1)Matter occupies the space:
The volume is the amount of space occupied by the material.
(2) Matter has mass:
Any kind of material visible and invisible, has certain amount of matter in it called as “mass”
Structure and composition of matter:
Matter is made up of very very small particles in it.
These particles which make up the matter are atoms, ions and molecules
.
• Atoms :
Atoms consist of nucleus which is positive charge at centre and electrons which possesses
negative charge as in cloud around it.
In case of sodium and helium they presence in combine form as lack of individual existence
to form molecules.
• Molecules:
These are the smallest distinct units into which a pure matter can be divided. They represent
the chemical and composition property of matter.
Combination of two or more atoms result in formation of molecule. Combine atoms may be
of one kind or different. Water is made up of hydrogen and oxygen where hydrogen molecule
is made up of two hydrogen atoms.
• Ions:
Ions may be positive or negative with respect to atoms or group of atoms. Atom or group of
atom transformed to form ions when they lose or gain the one or more electron.
Eg. Sodium ion (Na+
) , Chlorine ion (Cl-
)

States of matter:

On the basis of physical property namely temperature the matter is classified into
(A)Solid -ice
(B)Liquid- water
(C)Gas- air
By changing the temperature one can easily change the states of matter.
The characteristic of matter is depend upon the arrangement of atoms or molecules inside
the matter.
The molecules of matter are held together by force of attraction between them, called as
intermolecular force of attraction. And the space between molecules are called as
intermolecular space.
These arrangement of particles inside the matter decides whether is exist as solid , liquid or
gas.

Solid states:
Characteristic by structural rigidity and with definite shape and volume. Molecules are tightly
packed due to strong intermolecular force in between solid particles .

Properties of solid :

1. Have tightly packed particle
2. Possess fixed shape and fixed volume
3. Solid do not show fluidity
4. Cannot be compressed much
   Liquid state:
   Characterised by the change in its shape but resistivity towards change in its volume.
   They are less tightly packed as compared to solid. Within the liquid molecules are moving one
   position to another, indicating fluidity.
   Properties of liquid:
5. Have loosely packed particles.
6. Have fixed volume but do not have fixed shape , take the shape of container in which
   they are place
7. Liquid flow easily.
8. Liquid cannot be compressed much

Gaseous state:
State of matter which characteristic by its capacity to change its shape and size.
They are very loosely packed as compare with solid and liquid arrangement of molecules.
They do possess weak intermolecular forces which result in molecules are far apart.
They are free to move.

Properties of gases:

1. Particle within the gas , are loosely packed.
2. They take the whole shape and volume of the container in which they are kept as
   result of neither of fixed volume nor a fixed shape.
3. Gases easily flow.
4. Gases can be compressed with ease into small volumes.
   Effect of arrangement on the basis of their property:
   The property shown by matter is depend upon the arrangement present in it.
   o SOLID:
   In solid structure the molecules are closely packed, in such way that their position is almost
   fixed. Hence retained shape and volume. The intermolecular space is very small as the result
   of greater intermolecular force of attraction between solid particles.
   Application of heat onto solid, brings the extra energy to molecules and they begin to move
   apart from their position finally resulting in the state change from solid to liquid.
   o LIQUID:
   Intermolecular space in the liquid particle is more comparable to solid as result of which due
   to the weaker intermolecular force. That’s why the molecules are free to move.
   Hence liquid does not possess definite shape and it takes the shape of container.
   On heating liquid changes into vapour which is gaseous state. This is because on heating liquid
   molecules get or acquires energy and start moving with higher speed and near the surface or
   boundary get escape from the liquid and produce vapour.
   o GASES:
   Characteristic by fast moving particle with average speed of 1600km/hr.
   The intermolecular space is wide because of very weak intermolecular force of attraction
   between gas molecules.
   The molecular force of attraction is depend upon the density but due to low density the force
   is non-existence. Hence gas neither has shape nor have fixed volume.
   On cooling the density goes on increase result into establishment of intermolecular force
   which brings molecule closer and gas get converted into liquid