Periodic classification of elements

Subject: Periodic classification of elements

Introduction:-

Matter around us is present in the form of elements, compounds and mixtures.

Elements contain atoms of only one type .

Till now 114 elements are known to us.

Around 1800, only 30 elements were known.

All these had different properties.

More elements discovered with time ,so scientist gather more and more information about the properties of these elements.

Making order out of chaos - early attempts at the classification of elements.

Dobereiner's Triads:-

In 1817, Johann Wolfgang Dobereine, tried to arrange elements with similar properties into groups.

He identified some groups having three elements each.

So he called these groups 'traids'.

He showed that when three elements in a triad were written in order of increasing atomic masses; the atomic mass of the middle element was roughly average of the atomic masses of the other two elements.

For example:-

Atomic mass of Li =6.9

Atomic mass of Na = 23.0

Atomic mass of K = 39.0

Average of atomic masses Li and K = mass of Na

6.9+39.0/2 =mass of Na

45.9/2=mass of Na

22.95= 23.0(approx)=mass of Na

Limitations of Dobereiner's classification=

At that time 30 elements are known to exist but only 9 were classified in the form of 3 triads.

Newlands' law of octaves:-

In 1866, John Newlands' arranged the then known elements in order of increasing atomic masses.

He started with the element having he lowest atomic mass (Hydrogen) and ended at thorium which as the 56th element.

He found that every eighth element had the properties similar to that of the first .

He compared this to the octaves found in music.

Therefore, he called it the 'law of octaves'.

It is known as 'Newlands Law of Octaves'.

At that time 56 elements elements were known.

Limitations of Newlands'law of octaves:-

It is found that the Law of octaves was applicable only upto calcium as after Calcium every eighth element didn't possess properties similar to that of the first.

It is assumed by Newlands' that only 56 elements existed in nature and no more elements would be discovered in the future. But , later on , several new elements were discovered, whose properties didn't fir into the law of octaves.

In order to fit elements into his table, Newlands'adjust two elements in the same slot, but also put some unlike elements under the same note.

Example:- Cobalt and nickel are in the same slot and these are placed in the same column as fluorine, chlorine and bromine which have different properties then these elements.

Iron which resembles cobalt and nickel in properties has been placed far away from these elements.

Thus Newlands' Law of octaves worked well with lighter elements only.

Making order out of choas- Mendeleev's Periodic table :-

Dmitri Ivanovich Mendeleev  was the most important contributor to the early development of a periodic table of elements where in the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties.

When Mendeleev started his work , 63 elements were known.

He examined the relationship between the atomic masses of the elements and their Physical and chemical properties.

Among chemical properties, Mendeleev concentrated on the compounds formed by elements with oxygen and hydrogen.

He selected Hydrogen and oxygen as they are very reactive and formed compounds with most elements.

The formulae of hydride and oxides formed by an element were

treated as one of the basic properties of an element for its classification.

How he classify??

He took 63 cards and on each card he wrote down the properties of one element.

He sores out the elements with similar properties and pinned the cards together on a wall 

He observed that most of the elements got a place in a periodic table and were arranged in order of their increasing atomic masses.

It was also observed that there occurs a periodic recurrence of elements with similar physical and chemical properties.

On this basis, Mendeleev formulated a periodic law, which states that' 'properties of elements are the periodic function of their atomic masses.

Mendeleev's Periodic Table contains vertical columns called 'groups' and horizon rows called 'periods'.

Achievements of Mendeleev's Periodic table:-

While developing the Periodic Table, there were a few instances where Mendeleev had to place n element with slightly greater atomic mass before an element with a slightly lower atomic mass.

The sequence was Invented so that elements with similar properties could be grouped together.

For example, Cobalt appeared before nickel.

Atomic mass of cobalt = 58.9

Atomic mass of nickel = 58.7

He left some gaps in his periodic table and predicted the existence of some elements that had not been discovered at that time.

He named them by prefixing a Sanskrit numeral, Eka (one) to the name of preceding element in the same group.

Example:- scandium , gallium and germanium , discovered later, have properties similar to Eka-boron , eka aluminium and eka silicon, respectively. The properties of Eka aluminium predicted by Mendeleev and those of element , gallium which was discovered later and replaced eka aluminium.

Noble gases such as helium(He), neon(Ne) and argon(Ar) have been discovered very late because they are inert and present in low concentrations in our atmosphere. these could placed in a new group without disturbing the existing order.

Limitations of Mendeleev's classification:-

Electronic configuration of Hydrogen resemble that of alkali metal.

Like alkali metals Hydrogen combine with halogen, sulphur and oxygen to form compounds having similar formulae.

On the other hand like halogens, Hydrogen also exists as diatomic molecules and it combines with metals and non-metals  to form covalent compounds.

So , no fixed position can be given to Hydrogen in the periodic table. This was the first limitation of Mendeleev's Periodic table.

Isotopes were not considered.

Atomic mass donot increase in regular manner in going from one element to next.

So it was not possible to predict how many elements could be discovered between two elements.

Making order out of chaos – The modern periodic table:-

In 1913 , Henry Moseley showed that thr atomic number of an element is a more fundamental property than its atomic mass.

Modern periodic law:- property of an element is the periodic function of their atomic number

Position of elements in the modern periodic table:-

Modern periodic table has 18 vertical columns known as "groups" and 

7 horizontal rows known as period s.

Elements present in one group have same number of valance electrons.

For example :- Fluorine and chlorine belong to group 17 , so have 7 electrons in outermost shell.

Number of shells increase as we go down the group.

Atomic number increases by one unit on moving from left to right

Trends in modern periodic table:-

Valency :- the combining capacity of the element.

Example:- sodium:- 2,8,1 

Valency :- 1

Chlorine :- 2,8,7 

Valency:- 7

Carbon :- 2,8,4 

Valency :- 4

Atomic size:- It refers to radius of an atom.

It refers to distance between the centre of nucleus and outermost shell of an isolated atom.

Atomic radius of Hydrogen atom is 37pm.

Atomic radius decrease along the period.

Reason:- this is due to increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom.

Atomic radius increase along the group.

Reason:- this is because the distance between the nucleus and the outermost shell increase due to increase in number of shell.

Metallic and non-metallic properties:-

Metals tend to lose electrons while forming bonds . So they are electropositive in nature.

Down the group  electron loosing tendency increase and so metallic character increase.

Along the period effective nuclear charge increase and so metallic character decrease.

Non-metals are electronegative.

They tend to form bond by gaining electron.

Along the period non-metallic character increase.

Metal oxides are basic in nature.

Non-metal oxide are acidic in nature.

New kings and knigdom class 7 history

Chapter 2 :- New kings and kingdoms

1.Dynasty:-A family of rules who rules over a country for a long period of time.

2.Kingdoms:-Any country which is ruled by a monarch (king or queen) is considered to be a kingdom

3.Empire:-An empire can be said is a large kingdom. It is traditionally larger than a kingdom and many consists of many different regions and nations may be far away from head of kingdom i.e. it's capital.

The emergence of new dynasties:-

• By the seventh century there were big landlords or warrior chiefs in different regions of the subcontinent called Samantha's.
• They were expected to:-
• bring gifts for their kings ,
• be present at their courts
• provide military support.
• As Samantas gained power and wealth, they declared themselves to be maha-samanta, maha-mandaleshvara.
• Sometimes they asserted their independence from their overlords.
• For example:- Rashtrakuta(in the Deccan)were the sub-ordinate to Chalukyas of Karnataka initially.
•  But in mid eighth century, its chief, Dantidurga overthrew his Chalukya overlord and performed a ritual called hiranya-garbha.
• When this ritual was performed with the help of Brahmanas, it was thought to lead to re-birth of sacrifices as a Kshatriya, even if he was not one by birth.
• In other cases , men from enterprising families used their military skills to carve out kingdoms. 
• For example:- the Kadamba Mayurasharman and Gujarara- Pratihara Harichandra. were  Brahmanas who gave up their traditional professions and took up arms, successfully establishing kingdoms in Karnataka and Rajasthan respectively.

Administration in kingdoms:-

• Many kings adopted high -sounding titles such as maharaja-adhiraja, tribhuvana-chakravartin and so on
• Inspite of this, they share power with their Samantas as well as with association of peasants, traders and Brahmanas.
• In each of these states, resources were obtained from the producers and traders.
• These resources were used to finance the king's establishment, constuction of temples ,forts, in wars.

Prashastis and land grants:-

• Prashastis contain details that may not be literally true.
• It tells us how rulers wanted to depict themselves - as valiant, victorious warriors.
• These were composer by learned Brahmanas, who occasionally helped in the administration.
• Kings rewarded Brahmanas by grants of land. 
• These were recorded on copper plated, which were given to those who received the land.
• Note:- Ruler of Kanauj won a victory over Chakrayudha.
• A poem containing the history of kings who ruled over Kashmir is composed by author named Kalyana.

Warfare for wealth:-

Tripartite struggle:-

• Kanauj , a city in the Ganga valley was an important city of the time.
• 
  
• For centuries, rulers belonging to the Gujarat-Pratihara, Rashtrakuta and Pala dynasties fought for control over Kanauj . It is known as tripartite struggle.

Sultan Mahmud of Ghazni, Afghanistan:-

• He ruled from 997to 1030.
• He extended control over parts of Central Asia, Iran and North-western part of subcontinent.
• He raised the subcontinent almost every year.
• His targets were wealthy temples, including that is Somnath, Gujarat.
• He used wealth to create a splendid capital city at Ghazni.
• He hired a scholar named Al-Biruni to write an account of subcontinent.
• This Arabic work is known as Kitab ul-Hind.
• Other kings were Chahamanas , later known as the Chauhans, rulerld over the region around Delhi and Ajmer.
• The best Known Vhahamana ruler was Prithviraja III Who defeated Sultan Muhammad Ghori in 1191 but lost to him in 1192.

The Cholas:-

From Uraiyur to Thanjavur:-

• A minor chiefly family known as the Muttaraiyar held power in the Kaveri delta.
• They were subordinate to the pallava kings of Kanchipuram.
• Vijayalaya captured the delta from the Muttaraiyar in the middle of the ninth century.
• He built the town of Thanjavur and a temple for goddess Nishumbhasudini there.
• The successors of Vijayalaya conquered neighbouring regions and the kingdom grew in size and power.
• The Pandyan and the Pallava territories to the south and north were made part of this kingdom.
• Rajaraja I become king in 985 and expanded control over most of the area.
• Rajaraja's. Son Rajendra I continued his policies and even raided the Ganga valley, Sri Lanka and countries of Southern Asia, developing a navy for these expeditions.

Splendid Temples and Bronze sculpture:-

• The big temples of Thanjavur and Gangaikonda-cholapuram are architectural and sculptural marvels.
• These temples were built by Rajaraja and his son Rajendra.
• Chola temples often became the nuclei of settlements which grew around them.
• These were centres of craft production.
• Temples were endowed with land by rulers as well as by others.
• The product of this land went into maintaining all the specialists who worked at the temple and very often lived near it such as priests garland makers , cooks, sweepers, musicians, dancers etc .
• These temples were not only the place of worship , they were the hub of economic , social and cultural life as well.
• Amongst the crafts associated with temples the making of bronze images was the most distinctive.
• Chola bronze images are considered amongst the finest in the world.
• While most images were of deities sometimes images were made of devotees as well.
• Agriculture and irrigation:-
• Many of the achievements of the Cholas were made possible through new developments in agriculture.
• The river Kaveri branches off into several small channels before emptying into the Bay of Bengal.
• These Chennels overflow frequently, depositing fertile soil on their banks.
• Water from the channels also provide the necessary moisture for agriculture, particularly the cultivation of rice.
• Although agriculture had developed earlier in other parts of Tamil Nadu, it was only from the fifth or sixth century that this area was opened up for large scale cultivation.
• Forests had to be cleared in some regions, land had to be levelled in other areas.
• In the delta region embankments had to be built to prevent flooding and canals has to be constructed to carry water to the fields.
• In many areas two crops were grown in a year.
• In many cases it was necessary to water crops artificially. 
• A variety of methods were used for irrigation .
• In some areas well were dug.
• In other places huge tanks were constructed to collect rainwater.
• This irrigation require planning, organising labour and resources , maintaining these works.
• Most of the new rulers and people living in villages took an active interest in these activities.

The administration of the Empire:-

• The settlements of peasants(known as Ur) became.prosperous with the spread of irrigation agriculture. 
• Groups of such villages formed larger units called Nadu.
• The village council and the Nadu performed several administrative functions including dispensing justice and collecting taxes.
• Rich peasants of the Vellala Caste exercised considerable control over the affairs of the Nadu under the supervision of central chola government.
• The Chola kings gave some rich landowners titles like muvendavelan, araiyar etc.
• Brahmanas often received land grants or brahmadeya.
• As a result, a large number of Brahmana settlements emerged in the Kaveri valley as other parts of South India.
• Each brahmadeya was looked after by an assembly or Sabha of prominent Brahmana landholders 
• These assemblies worked very efficiently.
• Their decisions were recorded in detail in inscription, often on the stone walls of temples.
• Association of traders known as nagarams also occasionally performed administrative functions in towns.
• Inscription from Uttaramerur in Chingleput district, Tamil Nadu, provide details of the way in which Sabha was organised.
• The Sabha had separate committees to look after irrigation work , gardens, temples etc.
• Name of those eligible to members of these committees were written on small tickets of palm leaf.

Thank you:-)

Our environment class 10

Introduction:

• Everything around us that surrounds us is environment. It includes both living (biotic) and non-living (abiotic) components.
• Interaction between these biotic and abiotic Components form an ecosystem.
• In an ecosystem living Components depend upon each other for their food which gives rise to food chains and food webs in nature.
• In environment human activities lead to environmental problems such as depletion of ozone layer and production of huge amount of garbage.

Ecosystem:-

• All the interacting organisms in an area together with non-living constituents of the environment forms an ecosystem.E.g. Forests, ponds.
• Types of ecosystem:- Two types
• 1.Natural ecosystem:- The ecosystems which exists in nature on its own.
• Ex:- Forest, lake, ocean.
• 2.Artificial ecosystem:- Man-made ecosystem are called artificial ecosystem.
• Ex:- Crop field, garden, aquarium etc.

Components of ecosystem:- Two

• Abiotic (Air, water, soil) and  
• Biotic (planst and animals)

1.Biotic Component:- 

• All living Components forms biotic Component.
• Ex:- Plants, Animals, fungi etc.

2.Abiotic Component:-

• All non-living Components form an ecosystem.
• Ex:- air, water, land, light etc.

On the basis of nutrition biotic Components are further divided into:-

• Producers
• Consumers

Producers:-

• All green plants and blue green algae can produce their own food using abiotic Components (By photosynthesis)

Consumers:-

• Includes all animals which depends on producers directly or indirectly for their food.

Division of Consumers:-

• 1.Herbivores:- Feed on plants.
• Example:- Goat, deer.
• 2.Carnivores:- Feed on animal's Flesh.
• Example:- Tiger, Crocodile.
• 3. Omnivores:- Eats both plants and animals.
• Example:- Humans, Dog etc.
• 4.Parasites:- Organisms which live either in or on the body of host is called parasite. It is of two types:- ecto-parasite(e.g.lice, cascuta) and endo-parasite(e.g.Liver fluke).

Decomposers:-

• Organism which break down complex food substances into simpler ones.
• Or
• Organisation which feed on dead bodies of plants and animals. 
• Or
• Micro-organism which convert the dead plants and animals to humus.
• E.g. bacteria, fungi.
• Live in soil

Decomposition:- Process in which complex organic matter are broken down into simpler forms.

Rate of decomposition:- Several factors determine rate of decomposition.

• 1.Soil quality:- 
• ✓Abundance of micro-organism,
• ✓moisture content,
• ✓Temperature,
• ✓High aeration,
• ✓pH,
• 2.Compostion of organic matter:-
• 3.Climate.

Importance of decomposition:-

• Convert dead plant and Animals remains into humus.
• Improve soil fertility
• Nutrients are releasing back to soil.

Humus:- 

• Decomposer when eat upon dead plant and animal tissues, they convert them into a dark colour of substance called humus.
• Presence of humus ensures that the nutrients of the dead plants and animals are released into soil

Food chain:-

• Series of living organisms feeding on one another.
• 3 step food chain:-
•  grass -> deer -> lion
• 4 step food chain:-
• Plant -> goat -> fox -> lion
• 5 step food chain:-
• Grass -> insects -> frog -> snake -> eagle

Trophic level:- Each level of a food chain is called trophic level.

Food web:- Network of food chains is called food web. In nature food web exist.

Flow of energy between trophic level:-

• Flow of energy in a food chain is unidirectional.
• Green plants capture 1% of sunlight ad convert it into food energy.

10%Law:-

• Only 10% of energy is transferred to next trophic level. The remaining 90% energy is used in life processes by present trophic level.
• Due to gradual decrease in. Energy food chain contains 3-4 trophic levels.

Decrease in energy:-

1000KJ --> 100KJ --> 10KJ -->1KJ.

Biological magnification:-

• The concentration of harmful chemicals increases with every next trophic level in a food chain. This is caly biological magnification.
• Maximum concentratration of each chemical get accumulated in human bodies as  human occupy the top level in any food chain.

Food web:-

• In nature large numbers of chains are interconnected forming a food web.

Environmental problems:-

• Change in the environment affect us and our activities change the environment around us.
• Human activities leads to pollution, deforestation etc.

Ozone layer:-

• Protective blanket around the earth which absorbs most of harmful UV rays of sunlight, this protecting living beings from many health hazards such as skin cancer, cataract, destruction of plants etc.
• O3 (ozone) layer is present at higher levels of atmosphere.
• Sadly poison at ground level.

Formation ozone molecule:-

• 1.high energy of UV radiation breakdown the O2 molecules into free oxygen atom.
• O2 ( in presence of)-->O + O
• 2.These oxygen atoms combine with oxygen molecule O2 to form ozone molecule.

Depletion of ozone layer:- 

• The decrease in thickness of ozone layer over Antarctica was observed in 1985 and was termed as ozone hole.
• The decrease was linked to excessive use of synthetic chemicals like CFCs which is used in Refrigerators , ACs, fire extinguishers.
• UNEP [United Nations Environment Programme] succeeded in forging an agreement to stop CFC production at 1986 level by all counts.

Garbage Disposal:- 

• Improvements in lifestyle have resulted in accumulation of large amount of waste material

Types of material in Garbage:- 

1.) Biodegradable:-

• Substances which can be decomposed by the action of micro-organisms are called biodegradable waste.
• Ex:- Fruits, Vegetables peels, paper etc.

2.) Non-biodegradable:- 

• Substances which cannot be decomposed by the action of micro-organisms are called non-biodegradable waste.
• Example:- Plastic, metals, pesticides etc.
• Micro-organisms release enzyme which decompose the material but these enzymes are specific in their action that's why enzymes cannot decompose all the materials.

Methods of waste disposal:-

1.Biogas Plant:-

• Biodegradable waste can be used in biogas plant to produce biogas and manure.

2.Sewage treatment plant:-

• The drain waste can be cleaned in sewage treatment plant before adding it to rivers 

3.Land fillings:- 

• The wastes are buried in low lying areas and compacted by rolling with bulldozers

4.Composting:-

• Organic wastes are filled in a compost pit and converted with a layer of soil, after about three months garbage changes to manure.

5.Recycling:-

•  Non-biodegradable wastes are recycled to make new items.

6.Reuse:- 

• It is a conventional technique to use an item again.
• Example:- Newspaper for making envelops 

Thankyou...

Forests: Our Lifeline class 7 NCERT

Subject: Forest: Our Lifeline

• Large area of land covered with huge trees, shrubs (rose) and herbs(grass) is called forest.
• Forests serve as green lungs and water purifying systems in Nature.
• Plant variety in a forest:- Bamboo, Neem, Palash, Teak, Fig, Ferns, Mosses, Maple, oak, pine, sal, semal, Sheesham, Khair, Amla, kachnar.
• Animal variety in a forest :- boar, bison, jackals, porcupine, elephant.

Who has planted so many trees in forest?

->In nature, trees produce enough seeds. The forest floor provides favourable conditions for them to germinate and develop into seedlings and saplings. Some grow up into trees.

Layers of forest:- Three layers

1.Crown:-

•The branchy part of a tree above the stem is called as crown.

2.Canopy:-

•It is the structure formed by collection of individual plant crowns of a plant community.

3.Understorey in forest:-

•Plant layers growing beneath the forest canopy.

•Forest understory receive less intense light than the forest canopy.

Autotrophs:-Prepare their own food. e.g., plants, some algae and bacteria.

Heterotrophs:-

Depend on others for their food.e.g., animals, humans, fungi. 

It includes:-

      ✓Herbivores , 

      ✓Carnivores and

      ✓Omnivores.

Decomposer/Saprotrophs:- •Organisation which feed on dead bodies of plants and animals. 

Or

Micro-organism which convert the dead plants and animals to humus.

•E.g. bacteria, fungi.

•Live in soil

Decomposition:- Process in which complex organic matter are broken down into simpler forms.

Detritus:- Raw material for decomposition including dead plant remains , dead animals remains and faecal matter.

Rate of decomposition:- Several factors determine rate of decomposition.

1.Soil quality:- 

✓Abundance of micro-organism,

✓moisture content,

✓Temperature,

✓High aeration,

✓pH,

2.Compostion of organic matter:-

3.Climate.

Importance of decomposition:-

• Convert dead plant and Animals remains into humus.
• Improve soil fertility
• Nutrients are releasing back to soil.

Humus:- 

• Decomposers when eat upon dead plant and animal tissues, they convert them into a dark colour substance called humus.
• Presence of humus ensures that the nutrients of the dead plants and animals are released into soil.

Forests are called green lungs. Why?

Because plants release oxygen through the process of photosynthesis. The plants help to provide oxygen for animal respiration. They also maintain the balance of oxygen and carbon dioxide in the atmosphere . That is why forests are called lungs.

Food chain:- series of living organisms feeding on one another.

3 step food chain:-

 grass -> deer -> lion

4 step food chain:-

Plant -> goat -> fox -> lion

5 step food chain:-

Grass -> insects -> frog -> snake -> eagle

Trophic level:- Each level of a food chain is called trophic level.

Food web:- Network of food chains is called food web. In nature food web exist.

Threat to forests:-

Human activities pose a threat to forests.

Deforestation:- permanent destruction or conversion of forest areas for other purposes.

Cause of deforestation:-

•Overpopulation,

•Agriculture,

•Human settlement,

•Making furniture,

•Fuel

•Forest fires

Harmful effects of deforestation:-

•Loss of species,

•Soil erosion,

•Increased concentration of Carbon dioxide,

•Increase of earth's temperature,

•Lower ground water level,

•Destroy forest ecosystem.

•Possibility of flood increases

•Possibility of drought increase

Major Victims of deforestation:-

Plants and animals

IMPORTANCE OF FOREST:-

•Provide a home for many animals and plants.

•Provide useful products like gum, oils, spices, fodder for animals etc.

•Provide habitat to animals, birds and insects.

•provide food and shelter to many tribes

•support growth to plants

•maintain the balance of Oxygen and carbon dioxide in atmosphere so called green lungs

•furniture making

•Medicinal use of many plants

•control floods

•Natural absorber of rain water so help to Recharge ground water and thus maintain water table

•Prevent water logging in soil during heavy rainfall.

• Absorb noise 

Forest is a dynamic living entity.

i.e., it is full of life

Keyword:-

1.canopy:-It is the structure formed by collection of individual plant crowns of a plant community

2.Crown:-The branchy part of a tree above the stem is called as crown

3.Decomposers:-Organisation which feed on dead bodies of plants and animals. 

Or

Micro-organism which convert the dead plants and animals to humus.

•E.g. bacteria, fungi.

•Live in soil

4.Deforestation:-permanent destruction or conversion of forest areas for other purposes.

5.Humus:-Decomposers when eat upon dead plant and animal tissues, they convert them into a dark colouref substance called humus.

Presence of humus ensures that the nutrients of the dead plants and animals are released into soil

6.Regeneration:-Process of formation of new plant from old one.

7.Seed dispersal:-Seed dispersal is the movement, spread or transport of seeds away from the parent plant.

8.Soil erosion:-The removal of top fertile layer is called soil erosion.

9.Understorey:-Plant layers growing beneath the forest canopy.

•Forest understory receive less intense light than the forest canopy

Thankyou 😃😃....

Fibre to fabric class 7 NCERT

Subject: Fibre to fabric class 7 NCERT Notes

Fibres:- Thread/filament which forms constituent of various composite material.

Types of fibres:- two types

1. Natural fibres

2. Artificial fibres

Natural fibres obtained from plants and animals.

 Example:- Jute, Flax, Cotton, Hemp, Coir, tree wool, wool, silk etc.

Man-made fibres are called artificial fibres. 

Example:- Nylon, Rayon(Artificial silk), Polyester etc 

In this chapter we will learn about Animal fibres:- wool and silk

Fleece:- hair of sheep or yak from which wool obtained.

Animal fibre:-Fibres obtained from animals e.g. Wool and Silk

WOOL:- 

• Obtained from skin hair of fat animals.
• Wool comes from sheep, goat, yak and some other animals.

Why animals have such fur?

• Because hair trap a lot of air.
• Air is a bad conductor of heat 
• So hair keeps these animals warm.
• Wool is derived from these hairy fibres.

Types of fibres that obtained from sheep fleece:-

1. The coarse beard hair

2. The fine soft under- hair close to skin.

Fine hair provide the fibres for making wool.

Selective breeding:-

•  The process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, us terms 'selective breeding'.

Animals that yield wool:- 

• Commonly available wool in market is sheep wool.
• Yak wool is common in Tibet and Ladakh.
• Mohair is obtained from angora goats found in hilly region such as Jammu and Kashmir.
• Also obtained from goat hair.
• Under fur of Kashmir goat is soft and is used to woven into fine shawls called Pashmina shawls.
• Camel fur, Llama and Alpaca found in South America also yield wool.

FROM FIBRES TO WOOL:- 

For obtaining wool, sheep are reared. Their hair is cut and processed into wool.

Rearing and breeding of sheep:-

• Feeding sheep properly by providing them grass mixed with pulses, corn, Jowar, oil cakes and minerals.
• In winter, sheep are kept indoors and fed on leaves, grain and dry fodder.
• Certain breeds of sheep have thick coat of hair on their body which yields good quality wood in large quantities. 
• Once the reared sheep have developed a thick growth of hair, hair is shaved off for getting wool.

Sheep are reared in many parts of our country for wool. Some Indian breeds of sheep are listed below:-

PROCESSING FIBRES INTO WOOL:-

• The wool which is used for knitting sweaters or for wearing shawls is the finished product of a long process, which involves the following steps:-

STEP 1:- SHEARING:- 

• The fleece of sheep along with a thin layer of skin is removed from its body. This process is called shearing.
• The uppermost layer of skin of sheep is dead so it does not hurt the sheep.
• Hair removed during summer so that they enable to survive without protective coat of hair.

STEP 2:- SCOURING:- 

• Sheared skin is washed in tanks to remove grease, dust and dirt. This is called scouring.

STEP 3:- SORTING:-

• In factory , different textures of hairy skin are seperated .

STEP 4:- BURR PICKING:-

• Burr are small fluffy fibres 
• They are picked out from the hair.
• The fibres are scoured again and dried.
•  This is the wool ready to be drawn into fibres.

STEP 5:- DYEING:- 

• The fibres can be dyed in various colours the natural fleece of sheep and goats is black, brown and white.

STEP 6:- ROLLING INTO YARN:-

• The fibres are straightened, combed and rolled into yarn. 
• The longer fibres are made into wool for sweaters and shorter fibres are spun and woven into woollen cloth.

The process of fibres into wool can be represented as follows:-

Shearing ---> Scouring ---> Sorting ---> Cleaning of burrs ---> Dyeing ---> Rolling.

SILK:- 

• Animal fibres
• Silkworms spin the silk fibres.
• Rearing of silkworms for obtaining silk is called sericulture.

LIFE HISTORY OF SILK MOTH:-

• 1. Female silk moth lays eggs from which larva hatch .
• It's larva is called silkworms or caterpillars.
• 2. They grow in size, weave a net to hold itself .
•  It then swings its head from side to side 
• During movements of head the caterpillar secretes fibre made of a protein.
• This protein hardens on explosive to air and becomes silk fibre.
• 3. Soon the caterpillar completely covers itself by silk fibres and turn into pupa.
• This covering is known as cocoon.
• 4. Further development of pupa into moth continues inside the cocoon.

NOTE:- Soft silk yarn is as strong as a comparable thread of steel.

• The silk yarn (thread)  is obtained from the cocoon of silk moth.
• There is a variety of silk moth and so different types of silk is available to us such as tassar silk, mooga silk, kosa silk, eri silk etc 
• The most common silk moth is the mulberry silk moth.
• This silk is soft, lustrous and elastic and can be dyed in beautiful colours.

FROM COCOON TO SILK:-

• For obtaining silk, moth are reared and their cocoons are collected to get silk threads.

REARING SILKWORM:- 

• 1. Female silk moth lays hundreds of eggs at a time .
• 2. Farmers keep eggs under hygienic conditions and under suitable conditions of temperature and humidity.
• 3.Eggs are warned to a suitable temperature for the larvae to hatch from eggs.
• This is done when mulberry trees bear a fresh crop of leaves.
• 4. The larvae eat day and night and increased in size.
• After 20-30 days the caterpillars stop eating and move to a tiny chamber of bamboo in the tray to spin cocoons.
• The caterpillar or silkworm spins the cocoon inside which develops the silk moth.

PROCESSING SILK:- 

• A pile of cocoons is used for obtaining silk fibres.
• The cocoons are kept under the sun or boiled or exposed to steam.
• The silk fibres separate out.
• The process of taking out threads from the cocoon fro use as silk is called reeling of silk.
• Reeling is done by machine.
• Silk fibres are then spun into silk threads, which are woven into silk cloth by weavers.

KEYWORDS:-

1.COCOON:-The caterpillar completely covers itself by silk fibres and turn into pupa.

This covering is known as cocoon

2.FLEECE:-Hair of sheep or yak from which wool obtained.

3.REELING:-The process of taking out threads from the cocoon fro use as silk is called reeling of silk.

4.SCOURING:-Sheared skin is washed in tanks to remove grease, dust and dirt. This is called scouring

5.SERICULTURE:-Rearing of silkworms for obtaining silk is called sericulture.

6.SHEARING:-The fleece of sheep along with a thin layer of skin is removed from its body. This process is called shearing.

7.SILK MOTH:-A large moth with a caterpillar that spins a protective silken cocoon.

8.SILKWORM:-Worm whose caterpillar make silk fibre.

9.SORTING:-In factory , different textures of hairy skin are seperated .

Thankyou ....

Transformation of sentences

Part 1 

Type:-1 How to transform affirmative sentence into negative sentence??

1. Man is mortal.

Ans:-Man is not immortal.

2. You are wise.

Ans:-You are not foolish.

3. He is a rich man.

Ans:-He is not a poor man.

4.I am innocent.

Ans:-I am not guilty.

5.She is always careful.

Ans:-She is never careless.

6. He is doubtful.

Ans:-He is not sure.

7. She dislikes me.

Ans:-She does not like me. ( Do/does +v1)

8:-He is dishonest.

Ans:-He is not honest.

9.It is harmful.

Ans:-It is not harmless.

10. He was healthy.

Ans:-He was not unhealthy.

Type:-2 How to transform affirmative sentence into negative sentence by using "no/not + without".

1. I love you.

Ans:-I am not without love for you.

2.She was wise.

Ans:- She was not without wisdom.

3.Every cactus plant has a thorn .

Ans:-There is no cactus plant without a thorn.

4.Where there is a will there is a way.

Ans:-There is no way without will.

5.Everyone hates her.

Ans:-There is no one who does not hate her

6.He was hopeful.

Ans:-He was not without hope.

7.Every gain has risk.

Ans:-There is no gain without risk.

8. Everyone makes a mistake.

Ans:-There is no one who does not make a mistake.

9.Every rose has a thorn.

Ans:-There is no rose without a thorn.

10.You have money.

Ans:-you are not without money.

Type3:- How to transform affirmative sentence into negative sentence by using "to fail"

1. He saw the Taj Mahal.

Ans:-He did not fail to see the Taj Mahal.

2.My son plays cricket.

Ans:-My son does not fail to play cricket.

3.He will help the helpless.

Ans:-He will not fail to help the helpless.

4.When you are late , your father beats you.

Ans:-Your father does not fail to beat u when you are late.

5. You must have seen the Golghar when you went to Patna.

Ans:-You must not have failed to see the Golghar when you went to e

6.Speak the truth.

Ans:-Dont fail to speak the truth.

7.I failed to see her when she came in.

I did not see her when she came in.

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Part 2

Type4:- How to change "only/alone" to "none but" typed sentence.

1. Only a millionaire can afford such extravagance.

Ans:-None but a millionaire can afford such extravagance.

2. Only you can solve this problem.

Ans:-None but you can solve this problem.

3. The brave alone deserve the fair.

Ans:-None but the brave deserve the fair.

4. Only a foolish man would behave like this.

Ans:-None but a foolish man would behave like this.

5. Only the publisher has inspired me to write this book.

Ans:-None but the publisher has inspired me to write this book.

Type 5:-How to change "as soon as" to "no sooner ....then type" sentence

1. As soon as he saw me, he ran away.

Ans:-

2. As soon as I had reached the station, the train steamed off.

Ans:-

3. As soon as he arrives, he begins to work.

Ans:-

4. As soon as the bell rang, the boys ran out of their classes.

Ans:-

5. As soon as he came, he made objections

Ans:-

 

Type:-6 whenever/when ---> never but .

1. Whenever the child cries, the mother loves it.

Ans:-The child never cries but the mother loves it.

2. Whenever I go to you, I don't find you.

Ans:-I never go to you but I don't find you.

3. It always pours when it rains.

Ans:-It never rain but it pours.

4.Whenever she sees me , she is reminded of her lover.

Ans:-she never sees me but is reminded of her lover.

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Part 3

Type:-6 

1.He is as strong as I.

Ans:-

2.She is as tall as Nilu.

Ans-

3.He is as good as Aditya.

Ans:-

4.I know him as well as you do.

Ans:-

Type 7

1.He is more intelligent than I. 

Ans:-

2.You are duller than your brother.

Ans:-

3.The aeroplane flies faster than birds.

Ans:-

4.Iron is more useful than any other metal.

Ans-

5.Ashoka was greater than most other kings.

Ans:-

6.They have more money than honesty

Ans:-

Type :-8

1.Iron is the most useful of all metals.

Ans:-

2.America is the richest country in the world.

Ans:-

3.Kolkata is the largest town in India.

4.Ashoka was one of the greatest of king.

Ans:-

Part 4

Type :-9 

1.Mumbai is richer than any other town in India.

Ans:-

2.Delhi is better than all other towns in India.

Ans:-

3.Pt. Nehru was greater than all other men in India.

Ans:-

4.Gold is heavier than most other metals.

Ans:-

Type :-10

1.He is too proud to apologize.

Ans:-

2.He is too honest to accept a bribe.

Ans:-

Type 11

1.He is so kind hearted that he will forgive me.

Ans:-

2. The house is so large that it will accommodate all of us.

Ans:-

Type 12 

1.He is a good musician 

Ans:-

2.She is a woman of marked intelligence.

Ans:-

3.I abstain from wine.

Ans:-

4.My brother went to school everyday.

Ans:-

5.It is unique.

Ans:-

6.I lived only a few years in Darbhanga.

Ans:-

7.All the children wept.

Ans:-

8.Only a few persons would be cruel to a beggar.

Ans:-

9.I seldom go there.

Ans:-

10.The two brothers are alike.

Ans:-

11.They won all the matches.

Ans:-

Part 5 Transformation of negative sentence into affirmative sentence.

Type 1

1. Never tell a lie.

Ans:-

2.He was not gallant.

Ans:-

3.Your brother is not intelligent.

Ans:-

4.He will never forget her.

Ans:-

5.They are not industrious.

Ans:-

6.He doesn't believe in God.

Ans:-

7.We are not immortal.

Ans:-

8.You are not inferior.

Ans:-

9.He was not learned.

Ans:-

10. Nothing is impossible.

Ans:-

Type 2 

1.He is not without love for her.

Ans:-

2.I am not without honesty.

Ans:-

3.There is no girl who is not playing.

Ans:-

4.The author did not lead any book uncorrected.

Ans:-

5.There is no smoke without fire.

Ans:-

6.The two sisters are not unlike each other.

Ans:-

7.There was no one present who did not cheer.

Ans:-

8.No one could deny that she was pretty.

Ans:-

9.There is no thunder without lighting.

Ans:-

10.No body will deny that he did his best.

Ans:-Every body will admit that he did his best.

Part 6 Transformation of negative sentence into affirmative sentence.

Type 3:-

1.He did not fail to see the Qutub Minar.

Ans:-He saw the Qutub Minar.

2.My daughter didn't fail to respect her teacher.

Ans:-My daughter respected her teacher.

3.Yor didn't fail to obey your teachers.

Ans:-You obeyed your teachers.

4.He didn't buy the book.

Ans:-He failed to buy the book.

5.She did not fail to appear at the SBI Clerk examination.

Ans:-She appeared at the SBI Clerk examination.

Type 4:-

1.None but you wanted to help her.

Ans:-Only you wanted to help her.

2.None but Aditi can do this work 

Ans:-Only Aditi can do this work .

Or

     Aditi alone can do this work.

3.None but the rich can but this luxurious car.

Ans:-Only the rich can but this luxurious car.

4.None.but graduates can apply for this post.

Ans:-Only graduates can apply for this post 

Or 

     Graduates alone can apply for this post.

5.None but the brave deserve the fair.

Ans:-Only the brave deserve the fair.

Type 5:-

1.The child never cries but the mother loves it.

Ans:-Whenever the child cries , the mother loves it .

2.I never go to you but I do not find you.

Ans:-Whenever I go to you , I do not find you.

3.It never rains but it pours.

Ans:-It always pours when it rains.

4.She never sees me but is reminded of her lover.

Ans:-Whenever she sees me, she is reminded of her lover.

Type 6

1.He is not so fat as I .

Ans:-I am fatter than he.

2.Meena is not so beautiful as Veena.

Ans:-Veena is more beautiful than Meena.

3.He is not as good as Vikas.

Ans:-Vikas is better than he.

4.I am not as tall as you.

Ans:-You are taller than I.

5.No other bowler in the Indian Cricket team is so good as Jahir Khan.

Ans:-Jahir khan is better than any other bowler in the Indian Cricket team .

6.No other story book is so popular as the Arabian Nights.

Ans:-The Arabian Nights is more popular than all other story books.

Part 7 Transformation of negative sentence into affirmative sentence.

Type 7

1.He is not wiser than you.

Ans:-You are as wise as he.

2.I am not duller than you.

Ans:-You are as dull as I

3.She doesn't know you better than I do.

Ans:-I know you  as well as she does.

4.He does not have more money than honesty.

Ans:-He has as much honesty as money.

5.You can't run faster than a horse.

Ans:-A horse can run as fast as you.

6.Copper is not more useful than Iron.

Ans:-Iron is as useful as copper.

Type 8

1.No other peak in the world is as high as Mt. Everest.

Ans:-Mt. Everest is the highest peak in the world.

2. No other animal is so ferocious as the tiger.

Ans:-The tiger is the most ferocious in the world.

3.Very few buildings are so beautiful as the Taj Mahal.

Ans:-The Taj Mahal is one the most beautiful buildings.

4.Very few metals are as costly as gold.

Ans:-Gold is one of the costliest metals .

Type 9.

1 He is too clever not to understand the tricks.

Ans:-He is so clever that he will understand the trick.

2.Your speech is too impressive not to impress the audience.

Ans:-Your speech is so impressive that it will impress the audience.

Type10

1.He was so weak that he could not play.

Ans:-He is too weak to play.

2.The news is so good that it can't be true.

Ans:-The news is too good to be true.

Type 11 🌟

1.His services can't be forgotten.

Ans:-His services have been too great to forgotten.

Type 12

1.Your fortune did not improve with time.

Ans:-Your fortune became worse with time.

2.Dont make a noise.

Ans:-Keep quite.

3.He is no fool.

Ans:-He is a clever man.

4 Don't smoke here.

Ans:-Refrain from smoking here

5.He was asked not to smoke.

Ans:-He was prohibited from smoking.

6.I didn't find the road very bad.

Ans:-I found the road fair.

7.Not many people were present there.

Ans:-Only a few people were present there.

8.There is nothing similar in the world.

Ans:-Everything is dissimilar in the world.

9.Don't spit here.

Ans:-Refrain from spitting here.

10.She didn't live for many days in Patna.

Ans:-She lived for only a few days in Patna.

11.Lata is no mean singer .

Ans:-Lata is a good singer.

135 sentence covered .Ty

Class7 Inside our earth

Inside our earth:-

Introduction:-

• The earth is a dynamic planet.
• It is constantly undergoing changes inside and outside.

Interior of the earth:-

• The earth is made up of several concentric layers with one inside another.
• Crust:- The uppermost layer over the earth's surface is called crust.
• It is thinnest of all the layers
• It is about 35 Km on the continental masses and only 5 Km on the ocean floor.
• The main mineral constituents of continental mass are silica and alumina (sial).
• The oceanic crust mainly consists of silica and. Magnesium (Sima)
• Mantle:-Just beneath the crust is the mantle.
• It extends upto the depth of 2900 Km below the crust.
• Core:- Innermost layer with a radius of about 3500 Km
• Mainly made up of nickel and iron (nife , Fe= ferrous means iron).
• Central core has very high temperature and pressure.

Rocks and minerals:-

• Any natural mass of mineral matter that make up the earth crust is called rock.
• It can be of different colours, size and texture.
• Types of rocks:- three types
• Igneous rocks, Sedimentary rocks and metamorphic rocks.

Igneous rocks:-

• Also called primary rocks.
• When the molten magma cools, it becomes solid.
• Rocks thus formed is called igneous rocks.
• It is of two types:-
• Intrusive rocks,
• Extrusive rocks.
• Extrusive igneous rocks:-
• Lava is actually fiery red molten magma coming out from the interior of the earth on its surface
• When this molten lava comes on the surface of the earth, it rapidly cools down and become solid.
• The rocks formed in such a way on the crust is called  Extrusive igneous rocks
• They have very fine grained structures.
• Example:-basalts.
• Deccan plateau is made up of basalt rocks.
• Intrusive igneous rocks:-
• Sometimes the molten magma cools down deep inside the earth crust
• Solid rocks so formed is called intrusive igneous rocks.
• Since they cools down slowly they forms large grains.
• Example:- Granite.
• Grinding stones used to prepare paste/powder of spices and grains are made up of granite.

Sedimentary rocks:-

• Rocks roll down, cracks and hit each other and are broken down into small fragments.
• These small particles are called segments
• These segments are transported and deposited by wind, water etc.
• These loose segments are Compressed and harden to forms layers of rocks. 
• These types of rocks are called sedimentary rocks.
• For example:- sand stones is made from grains of sands.
• These rocks also contains fossils of plants, animals and other micro-organism that once lived on them.

Metamorphic rocks:-

• Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure
• For example:-
• Clay changes to slate
• Limestone changes to marble.

Importance of rocks:-

• Rocks are very useful to us.
• Hard rocks are used to make roads, houses and building.
• Rocks are used in many games such as seven stones (pitthoo), hopscotch(stapu), five stones (gitti)

Rock cycle:-

• One type of rock changes to another type under certain conditions in a cyclic manner. This process of transformation of rock from one to another is called rock cycle.
• When the molten magma cools, it solidify to becomes igneous rocks.
• These igneous rocks are broken down into small particles that are transported and deposited to form sedimentary rocks
• When the igneous and sedimentary rocks are subjected to heat and pressure they change into metamorphic rocks
• The metamorphic rocks which are still under great heat and pressure melt down to form molten magma.
• The molten magma again cools down and again cools down and solidify into igneous rocks.

Rocks are made up of minerals.

• Minerals are naturally occurring substances which have certain physical propertiesand definite chemical composition.
• Minerals are very important to man- kind.
• For example:- coal, petroleum and natural gas are used as fuel.
• Iron, aluminium, uranium, gold etc are used in industries, in medicine and in fertilizers etc.

More to know:-

• The deepest mine in the world is in South Africa. It is about 4 Km deep .
• In search of oil engineers have dug a hole about 6 Km deep.
• To reach to the centre of earth , we have to dig a hole about 6000Km deep on the ocean floor.
• The crust forms only 1% of the volume of earth, 84% consists of mantle and 15% make core.
• The radius of earth is 6371Km.
• Latin words :- igneous = fire; sedimentary= settle down; metamorphic= change of form.
• Fossils:- The remains of dead plants and animals trapped in the layer of rocks is called fossils.