CLASS 6TH | COMMON LABORATORY APPARATUS AND EQUIPMENT | REVISION NOTES

Chemistry is a fascinating science, full of unusual trivia. Chemistry is indeed in our everyday life. We find chemistry in the food we eat, the air we breathe, cleaning products, our emotions and literally every object we can see or touch.

Chemists use all kinds of equipment in their labs to run their experiments. In this topic, you will see some of the most common pieces of equipment and their uses and also precautions to be taken in the chemistry lab.

When performing experiments, taking accurate measurements is crucial. There are a wide variety of measurements that can be taken depending on the task at hand. 

In this chapter, you will find a table which contains images of basic apparatus and how to use each piece of equipment in the laboratories.

Common laboratory apparatus and equipment

We must use our everyday experiences to understand various natural phenomena. In living beings, observation employs the senses. In science, observation can also involve the recording of data using instruments. It also refers to any data collected during the scientific activity. Careful observations help us to draw scientific conclusions.

 A chemistry laboratory helps students to:

  • Observe and see for themselves.
  • Understand the difference between different compounds.
  • Learn the importance of observation and experiment.

Precautions to be taken in the chemistry lab

Safety is a key concern in any scientific enterprise, but particularly in the chemistry laboratory. There are many potential hazards when working with chemicals, but all of them can be avoided with the appropriate precautions.

  • Always wear an apron to protect your clothes.
  • Never work alone with chemicals.
  • Never touch or taste any substance.
  • Use small quantities of substances.
  • While heating substances, stand away from the burner and hold the tube away from yourself to avoid splashing.
  • Arrange apparatus and reagents in an orderly manner before starting the experiment
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CLASS 6TH | TYPES OF AGRICULTURE | REVISION NOTES

Types of Farming

The cultivation methods depend upon the characteristics of the physical environment, technological know-how and socio-cultural practices. Farming varies from subsistence to commercial type. In different parts of India, the following farming systems are practised.

Primitive Subsistence Farming

It is a ‘slash and burn’ agriculture. Farmers clear a patch of land and produce cereals and other food crops. When the soil fertility decreases, the farmers shift and clear a fresh patch of land for cultivation. It is known by different names in different parts of the country. It is known as jhumming in north-eastern states.

  • Land productivity is low in this type of agriculture.
  • This type of farming depends on monsoon.
  • This farming is practised in a few parts of India.

Intensive Subsistence Farming

  • This type of farming is practised in areas of high population pressure on land.
  • It is labour-intensive farming, where high doses of biochemical inputs and irrigation are used for higher production.

Commercial Farming

This type of farming uses higher doses of modern inputs such as high yielding variety (HYV) seeds, chemical fertilisers, insecticides and pesticides to obtain higher productivity.

Plantation is a type of commercial farming in which a single crop is grown on a large area. Plantations cover large tracts of land, using capital intensive inputs, with the help of migrant labourers. All the produce is used as a raw material in industries.

Eg: Tea, Coffee, Rubber, Sugarcane, Banana.

Cropping Pattern

India has three cropping seasons:

  1. Rabi
  2. Kharif
  3. Zaid
RabiKharifZaid
Sowing SeasonWinter from October to DecemberBeginning of the rainy season between April and MayIn between the Rabi and the Kharif seasons, there is a short season during the summer months known as the Zaid season (in the months of March to July)
Harvesting SeasonSummer fromApril to JuneSeptember-October
Important CropsWheat, Barley, Peas, Gram and Mustard.Paddy, Maize, Jowar, Bajra, Tur (Arhar),Moong, Urad, Cotton, Jute, Groundnut andSoyabean.Watermelon, Muskmelon, Cucumber,Vegetables and Fodder crops

Major Crops in India

A variety of food and non-food crops are grown in different parts of India, depending upon the variations in soil, climate and cultivation practices. Major crops grown in India are:

  • Rice
  • Wheat
  • Millets
  • Pulses
  • Tea
  • Coffee
  • Sugarcane
  • oil seeds
  • Cotton
  • Jute

We will discuss all of these one by one, in detail.

Rice

  1. It is a kharif crop.
  2. It requires high temperature and high humidity with annual rainfall above 100 cm.
  3. India is the second largest producer of rice in the world after China.
  4. It is grown in the plains of north and north-eastern India, coastal areas and the deltaic regions.

Wheat

  1. This is a rabi crop.
  2. It requires a cool growing season and bright sunshine at the time of ripening.
  3. It requires 50 to 75 cm of annual rainfall evenly distributed over the growing season.
  4. The Ganga-Satluj plains in the north-west and black soil region of the Deccan are two main wheat-growing zones in India.
  5. It is the second most important cereal crop and main food crop, in the north and north-western part of India.

Millets

  1. Jowar, Bajra and Ragi are the important millets grown in India.
  2. These are known as coarse grains and have very high nutritional value.
JowarBajraRagi
3rd most important food crop with respect to area and production.Grows well on sandy soils and shallow black soil.It is a crop of dry regions.
It is a rain-fed crop mostly grown in the moist areas.Grows well on red, black, sandy, loamy and shallow black soils.
Mainly produced in Maharashtra, Karnataka, Andhra Pradesh and Madhya Pradesh.Major producing states are Rajasthan, Uttar Pradesh, Maharashtra, Gujarat and Haryana.Major producing states are Karnataka, Tamil Nadu, Himachal Pradesh, Uttarakhand, Sikkim, Jharkhand and Arunachal Pradesh.

Maize

  1. It is a Kharif crop.
  2. It requires temperature between 21°C to 27°C and grows well in old alluvial soil.
  3. It is used both as food and fodder.
  4. Major maize-producing states are Karnataka, Madhya Pradesh, Uttar Pradesh, Bihar, Andhra Pradesh and Telangana.

Pulses

  1. India is the largest producer and consumer of pulses in the world.
  2. Pulses are the major source of protein in a vegetarian diet.
  3. Major pulses grown in India are Tur (Arhar), Urad, Moong, Masur, Peas and Gram.
  4. Pulses are mostly grown in rotation with other crops so that the soil restores fertility.
  5. Major pulse producing states are Madhya Pradesh, Rajasthan, Maharashtra, Uttar Pradesh and Karnataka.

Food Crops other than Grains

Sugarcane

  1. It is a tropical as well as a subtropical crop.
  2. It grows well in hot and humid climates with a temperature of 21°C to 27°C and annual rainfall between 75cm to 100cm.
  3. It can be grown on a variety of soils.
  4. Needs manual labour from sowing to harvesting.
  5. India is the second largest producer of sugarcane only after Brazil.
  6. Sugarcane is the main source of Sugar, Gur (Jaggery), Khansari and molasses.
  7. The major sugarcane-producing states are Uttar Pradesh, Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh, Telangana, Bihar, Punjab and Haryana.

Oil Seeds

Different oil seeds are grown covering approximately 12% of the total cropped area of India. Main oil-seeds produced in India are:

  • Groundnut: is a Kharif crop and accounts for half of the major oilseeds produced in India. Gujarat is the largest producer of groundnuts.
  • Mustard: is a rabi crop.
  • Sesamum (til): is a Kharif crop in the north and rabi crop in south India.
  • Castor seeds: It is grown as both Rabi and Kharif crop.
  • Linseed: is a rabi crop.
  • Coconut
  • Soyabean
  • Cotton seeds
  • Sunflower

Tea

  1. It is also an important beverage crop introduced by the British in India.
  2. The tea plant grows well in tropical and sub-tropical climates with deep and fertile well-drained soil, rich in humus and organic matter.
  3. Tea bushes require warm and moist frost-free climate all through the year.
  4. Tea is a labour-intensive industry.
  5. Major tea producing states are Assam, hills of Darjeeling and Jalpaiguri districts, West Bengal, Tamil Nadu and Kerala.

Coffee

Yemen coffee is produced in India and this variety of coffee is in great demand all over the world. Its cultivation was introduced on the Baba Budan Hills and is confined to the Nilgiri in Karnataka, Kerala and Tamil Nadu.

Horticulture Crops

India is a producer of tropical as well as temperate fruits. Major crops produced are pea, cauliflower, onion, cabbage, tomato, brinjal and potato. Some of the famous horticulture crops grown in India are:

  • Mangoes of Maharashtra, Andhra Pradesh, Telangana, Uttar Pradesh and West Bengal Oranges of Nagpur and Cherrapunjee (Meghalaya), bananas of Kerala, Mizoram, Maharashtra and Tamil Nadu.
  • Lichi and Guava of Uttar Pradesh and Bihar
  • Pineapples of Meghalaya
  • Grapes of Andhra Pradesh, Telangana and Maharashtra
  • Apples, pears, apricots and walnuts of Jammu and Kashmir and Himachal Pradesh

Non-Food Crops

RubberFibreCottonJute
It is an equatorial crop.Cotton, Jute, Hemp and Natural Silk are the four major fibre crops.It is a Kharif crop.It is known as the golden fibre.
It requires a moist and humid climate with rainfall of more than 200cm and temperature above 25°C.Cotton, Jute and Hemp are grown in the soil.It requires hightemperature, light rainfall, 210 frost-free days and bright sunshine for its growth.It grows well on well-drained fertile soils in the flood plains. High temperature is required for its growth.
It is an important industrial raw materialNatural Silk is obtained from cocoons of the silkworms fed on green leavesCotton growswell in black cotton soil of the Deccan plateau.It is used in making gunny bags, mats, ropes, yarn, carpets and other artefacts.
Mainly grown in Kerala, Tamil Nadu, Karnataka and Andaman and Nicobar islands and Garo hills of Meghalaya.Rearing of silkworms for the production of silk fibre is known asSericulture.Major cotton-producing states are Maharashtra, Gujarat, Madhya Pradesh, Karnataka, Andhra Pradesh,Telangana, Tamil Nadu, Punjab, Haryana andUttar Pradesh.Major jute producing states are West Bengal, Bihar, Assam, Odisha and Meghalaya.

Technological and Institutional Reforms

Agriculture provides a livelihood for more than 60% of its population, so this sector needs some serious technical and institutional reforms. The Green Revolution and the White Revolution were some of the reforms initiated by people to improve agriculture.

Some Initiatives taken by the Government are:

  • Schemes introduced by Government such as Kissan Credit Card (KCC), Personal Accident Insurance Scheme (PAIS).
  • Special weather bulletins and agricultural programmes for farmers on the radio and television were introduced.
  • The government also announces minimum support price, remunerative and procurement prices for important crops to check the exploitation of farmers by speculators and middlemen.

Contribution of Agriculture to the National Economy, Employment and Output

  • In 2010-11 about 52% of the total workforce was employed by the farm sector.
  • The share of agriculture in the GDP is declining.
  • Indian Council of Agricultural Research (ICAR), agricultural universities, veterinary services and animal breeding centres, horticulture development, research and development in the field of meteorology and weather forecast, etc. are a few of the initiatives introduced by the government to improve Indian agriculture.
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CLASS 6TH | THE CIRCULATORY SYSTEM | REVISION NOTES

The transport system in the body is called as circulatory system.


Circulatory system in Human Begins:


The human circulatory is consist of heart, blood and blood vessels and lymphatic system.
It is also called as circulatory system.


Human Heart:


The human heart is pinkish coloured about size of fist. It is located in between two lungs in
rib cage. It has four hollow chambers with two thin walled auricles and two thick walled
ventricles. These chambers mean to prevent the mixing of pure and impure blood. There
interventricular septum which separates right and left ventricles.

  1. Auricles:
    Also termed as atrium. Theses arte upper chambers of the heart with thin walls and receive
    blood from different parts of body. The right auricle revives impure blood while left auricle
    receives pure blood.
  2. Ventricles:
    These are lower chambers of heart with thick walls as they have to pump the blood to outside.
    The right ventricle pumps impure blood while left ventricle pumps pure blood. The septum
    divided the heart into left and right sides.
    The Blood:
    Blood is red coloured fluid which as as connective tissue which supply nutrient as well remove
    waste from all body parts.
    Human body contain on average 5 litre of blood.
    Components of blood:
    Plasma : (60% In blood)
    It is liquid part of blood contains 90-92% of water , 7% protein 1% inorganic salts and about
    0.1%glucose and traces of other substances.
    Blood cells: (40%)
    This is cellular part of blood. There are three types of cells in human blood such as red cells,
    white blood cells and blood platelets.


Red Blood Cells
• Also called as erythrocytes. They are minute, biconcave circular structure, found about
5.5million/mm3
.
• They contain more haemoglobin as they get mature and loses nucleus, ribosomes and
mitochondria.
• Oxygen combines with haemoglobin to form oxyhaemoglobin and when carbon
dioxide combines with it forms carbaminohaemoglobin.
• Red cells transport whole absorbed oxygen as they lack in mitochondria.
• They are produce in long bone’s marrow and having the life span about 120 days
White Blood Cells:
• Called as leucocytes
• They are large , irregular or oval colourless nucleated structure. They are found to be
7000/mm3
in an adult.
• They are produced in red bone marrow and lymph nodes.
Leucocytes are of two types:
(A)Granulocytes are subdivided into acidophil, Basophils and Neutrophils.
(B)Agranulocytes : without granules and contain unlobed nuclei. Divided into lymphocytes
and monocytes. Lymphocytes performed phagocytic action against infection causative
agents. They have lifespan of about two weeks.
• The lifespan of WBC’s ranges from 12 hours to 12 days
Blood platelets:
• They are termed as thrombocytes, found about 2,50,000/mm3 of blood.
• They are oval, round or rod like cytoplasmic structure with only granules.
• Blood clotting is the main function of platelets in order to prevent excessive blood loss
Blood Groups:
Karl Landsteiner discovered the blood grouping system
Blood group are distinguished on the basis of presence of antigen and antibody.
Antigens are foregn bodies which are capable of generating an immune responsein the body
where as Antibodies are proteins that are produced by the body, as they work fight against
the antigens.
Four types of blood groups: A, B , AB, O in human beings on presence or absence of antigen
and antibodies.


Blood vessels:


Blood vessels form network of tubes which carry blood away from the heart and towards
heart.


They perform transportation and divided into following:
o Arteries:
Carries oxygenated blood from heart and transported to all body tissues (Except pulmonary
artery which carries deoxygenated blood)
They have thick and muscular wall and elastic to withstand the blood pressure
Lumen of arteries is small and lack valves
Smallest artery called as arterioles.


o Ventricles:
Carries deoxygenated blood to heart (except pulmonary vein which carry oxygenated blood)
The walls of veins are thin less muscular and non-elastic. They do possess valve and blood
flows through it with little pressure.
Small veins are called as venules .
Vein collapse when empty..


o Capillaries:
They are microscopic vessels
They are terminal branches of artery and re-join to give rise to vein.
Thin layer of it, enables for exchanging nutrients oxygen and carbon dioxide along with
tissues.


Blood circulation:


• The pumping action of heart starts by initiation of heart contraction of its muscular
walls
• Alternate contraction and relaxation continues regularly
• The right auricle receives blood rich in carbon dioxide from two major veins , vein lie
in back and front of heart.
• The blood the flows from right auricle to the right ventricle and then to the lungs
through the pulmonary artery.
• The gaseous exchange in the lungs turns the deoxygenated blood to pure blood
,makes it rich in oxygen.
• This blood reaches to left auricle through the pulmonary veins. It then passes to the
left ventricles
• From the left ventricles, the oxygenated blood is pumped into aorta , which is largest
artery in the body and is supplied to all the body parts.


Blood pressure:


The pressure exerted on wall of blood vessels is called as blood pressure.
▪ Upper limit of blood pressure is called systolic pressure , which ranges from
100-140 mm of Hg
▪ Lower limit of blood pressure called as diastolic pressure, which ranges from
60-80 mm of Hg
When person having more than 140 mm systolic and 90mm diastolic is consider to be
suffering from Hypertension or high blood pressure.
Blood pressure is measured by Sphygmomanometer.
The Heart Beat:
The contraction of auricle and ventricles produce a sound called as Heart-beat
The sequence of events taking place during one complete heartbeat is known as cardiac cycle.
The contraction phase is systole followed by relaxation phase is diastole.
Heart beat last for 0.85 seconds.
During each heartbeat, two sounds are produced. The contraction of auricles produces weak
sound which is followed by string sound produced by contraction of ventricles.
Heartbeat can by listen by stethoscope.


Pulse:


The rhythmic beating of the arteries due to beating of the heart is called pulse.
This rhythm or simply wave can be felt anf counted in the superfacial and radial arteries near
wrist. This count represent the count of heart beat.

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CLASS 6TH | RESPIRATORY SYSTEM | REVISION NOTES

Respiration – The process, in which the energy is released by breaking down food for
life activities, is called respiration.


Stages of Respiration – The process of respiration take place in two stages –


Breathing or external respiration – It involves the inhalation of oxygen rich air and
exhalation of carbon dioxide rich air.
Cellular or internal respiration – It causes breakdown of glucose with the help of
oxygen into CO2, water and energy.
C6H12O6 (Glucose) + 6O2 (Oxygen) 6CO2 (Carbon dioxide) + 6 H2O + Energy (38 ATP)


Site for respiration – This process partially takes place in cytoplasm and partially in
mitochondria of the cell.


Types of Respiration –


Aerobic Respiration – This respiration results in the breakdown of glucose in the
presence of oxygen.
Anaerobic – This respiration results in the breakdown of glucose in the absence of oxygen.
C6H12O6 2 C2H5OH + 2CO2 + 2ATP


Respiratory System in Humans –
The passage through which the exchange of gases takes place is called respiratory tract. It
involves various organs like nose, nostrils, nasal cavity, pharynx, larynx, trachea, bronchi,
bronchioles, alveolar sacs, and alveoli.


Exchange of gases –
In this process, we inhale oxygen rich and exhale carbon dioxide rich air.
Breathing – It is the process by which we take oxygen rich air in our body and air rich in
carbon dioxide is taken out from our body.
Breathing rate – breathing rate of a woman is faster than a man and it is not always
constant.
For an adult – 15 to 18 times in a minute


Mechanism of breathing – Breathing takes place in lungs. The air passes through nasal
cavity and windpipe and reaches to lungs. Breathing involves the movement of ribcage and
diaphragm.

It includes –
Inspiration or inhalation – taking in oxygen
Expiration or exhalation – giving our carbon dioxide


Common respiratory diseases –


Asthma – caused due to allergy and respiratory passage becomes swollen and
constricted.
 Bronchitis – it is the swelling of lining of bronchial tube. It makes breathing difficult.
Pneumonia – it is the inflammation of lungs tissue.
Tuberculosis – it is the infectious disease that affects the lungs

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CLASS 6TH | DIGESTIVE SYSTEM | REVISION NOTES

The Human Digestive System


Nutrition – It is a process which involves the utilization of food by an organism
to give out energy for growth and development.


Stages of Nutrition in Humans –

  1. Ingestion – process of taking food into the body
  2. Digestion – breakdown of large insoluble food molecules into small
    water soluble molecules.
  3. Absorption – the digested food is absorbed and passed through the
    intestinal wall into the bloodstream.
  4. Assimilation – process of utilization of absorbed food
  5. Egestion – elimination of undigested food.
    Human Digestive System – The digestive system is made up of two parts.
  6. Alimentary canal – It is a muscular and tubular structure which starts
    from the mouth and ends at the anus. The important parts of alimentary
    canal are
    i. Mouth – the ingestion and digestion of food starts here.
    ii. Pharynx – it receives food from the mouth and air from the nose
    to throat. It is meant only for food to pass through.
    iii. Oesophagus – also known as food pipe. It connects pharynx to the
    stomach.
    iv. Stomach – it a muscular, J shaped, bag like structure. The food is
    churned and gets mixed well with the digestive juices.
    v. Small intestine – Most of the digestion and absorption of nutrients
    and minerals from the food takes place here.
    vi. Large intestine – It is mainly involved in absorption of water from
    the undigested food.
    vii. Rectum
    viii. Anus
  7. Digestive glands – These are associated with alimentary canal. They
    secret enzymes that speed up the biochemical reaction and aid in
    digestion of food. In digestive system, there are –

  1. i. salivary glands
  2. a. submandibular
  3. b. sublingual and
  4. c. parotid
  5. ii. Pancreas – It secrets pancreatic juices which are poured into small
  6. intestine along with bile.
  7. iii. Liver – It is the largest gland of the body. It secretes bile juice.
  8. Process of Digestion – It involves the breakdown of complex food
  9. molecules into simpler food particles. There are seven different stages of
  10. process of digestion. These are –
  • In mouth – breakdown of carbohydrates
  • In the pharynx and oesophagus
  • In the stomach
  • Food in small intestine
  • Absorption of digested food in the small intestine
  • In the large intestine
  • Assimilation
    Enzymes and their functions – they are proteins which act as biological
    catalysts.
    Properties of enzymes –
  • They are more active at optimum temperature.
  • They are not destroyed during catalysis and can be reused.
  • They are sensitive to pH.
  • They are specific in their actions.
  • They are needed in small amount.
    Indigestion – it is a common condition which is related to upset
    stomach. It is also called dyspepsia.
    Symptoms –
  • Pain or discomfort in belly.
  • Bloating (Swelling of stomach)
  • Sense of uncomfortably full after eating.
  • Heartburn – it is caused due to the release of acid by stomach.


Healthy eating habits –

  1. Eat healthy food like green leafy vegetables
  2. Eat food slowly helps in detecting hunger.
  3. Eat oats and other fibre rich grain.
  4. Have a regular family meal.
  5. Always turn the TV off while having meal.
    Unhealthy eating habits –
  6. We should never skip breakfast as doing so drains out energy from
    our body.
  7. Energy large amount of food in one sitting is also an unhealthy eating
    habit that should be avoided.
  8. Eating food while watching TV, working, reading, even cooking food
    is also unhealthy eating behaviour.
  9. Eating junk and oily food also sets you up for even gain.
  10. Consuming sugar in large amount is also an unhealthy eating habit.
    Ways to keep oneself healthy –
  11. Eating many small meals instead of two or three meals.
  12. Avoiding snacks at last time.
  13. Avoiding spicy food and coffee.
  14. Avoiding smoking and chewing tobacco.
  15. Avoiding laying down immediately just after eating food
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CLASS 6TH | CELL- THE STRUCTURE AND FUNCTIONS | REVISION NOTES

Cell – it is the basic structural and fundamental unit of an organism. These are
called building blocks of our body.


Discovery of Cell – The term cell is first coined by an English scientist Robert
Hook in 1665. He used microscope to see a thin slice of dead cork. In this slice,
he observed some honeycomb like structures and he named them cell.


Microscope – A device used to see very tiny objects that are not visible to
naked ayes.


Cell theory – On the basis of remarkable findings, the basic features of modern
cell theory states that –
a. All living things are made up of one or more cells.
b. Cells are the basic structural and functional unit of organisms.
c. The chemical composition and metabolic processes of all the cells is
same.
d. All new cells are arises by the division of pre-existing cells.


Number, Shapes and Size of the Cell – Cells greatly differ in their shape, size
and number like organism such as bacteria is made up of single cell. Hence,
called unicellular and organism which are made up of multiple organism like
humans are called multicellular organisms.

  • Cells can be irregular, oval, oblong, elongated and thread like in shape.
  • Mostly cells are microscopic.
    Cell – the structural unit of life
    Cells vary in their shape, size and number. However, the basic structural
    components are same. Every organism like plants, animals and humans are
    made up of cells.
    Cell – the functional unit of life
    All the life processes performed by our body are due to the activity of cells
    present in our body. Example – root cells of plant absorb water and mineral
    from the soil.


Basic structure of the cell –

The prime components of a cell are –

  1. Cell membrane – It forms the outer boundary of the cell. It is known as
    plasma membrane in plant cell. It is living.
  2. Cell wall – It is the outermost protective layer of a cell. It is non-living.
  3. Nucleus – It is the small spherical mass present in the centre of
    cytoplasm. It has a surrounding membrane called nuclear membrane. It
    contains chromosomes. It regulates and controls various activities in a
    cell.
  4. Cytoplasm – It is a semi-liquid substance enclosed by cell membrane.
  5. Cell Organelles – Some of the main cell organelles present in cytoplasm
    are –
    i. Endoplasmic reticulum
    ii. Ribosome
    iii. Mitochondria
    iv. Golgi bodies
    v. Lysosome
    vi. Centrosome
    vii. Plastids
    viii. Vacuoles
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CLASS 6TH | MINERALS AND ORES EXERCISES| REVISION NOTES

Minerals are those in which individual crystals are composed of unit cells or basic unit layers of two or more types. Minerals are inorganic catalysts that function as regulators of metabolic activities in the body.

Isolation of elements in Chemistry class 12th aims to teach the students about the various processes of extraction of metals from ores. Very few metals such as the noble metals, i.e., Gold, Silver, Platinum, etc are present in their original metallic forms in nature.

Metallurgy is the field of science which deals with the extraction of metals from ores which are naturally found in the environment. Most of the elements especially metals are presently combined with other elements and these are called minerals.

An element may combine with a variety of other elements to make myriad minerals but out of them, only a few are viable sources of that metal. Such sources are called ores. Let’s have a brief look into some ores and minerals.

AluminiumBauxite
Kaolinite (a form of clay)
AlOx(OH)3-2x [where 0 < x < 1] [Al2 (OH)4 Si2O5]
IronHaematite
Magnetite
Siderite
Iron pyrites
Fe2O3
Fe3O4
FeCO3
FeS2
CopperCopper pyrites
Malachite
Cuprite
Copper glance
CuFeS2
CuCO3.Cu(OH)2
Cu2O
Cu2S
ZincZinc blend/Sphalerite
Calamine
Zincite
   ZnS
ZnCO3
ZnO

Extraction of Ores And Minerals

The process of extracting metal ores buried deep underground is called mining. The metal ores are found in the earth’s crust in varying abundance. The extraction of metals from ores is what allows us to use the minerals in the ground! Ores are very different from the finished metals that we see in buildings and bridges. They consist of the desired metal compound and the impurities and earthly substances called gangue.

The extraction of metals and their isolation occurs over a few major steps.

  • Concentration of Ore
  • Isolation of metal from concentrated Ore
  • Purification of the metal

Difference between Ores and Minerals

Here we have provided the major differences between Minerals and Ores.

MineralsOres
All the naturally occurring substances that are present in the earth’s crust are known as Minerals.Ores are usually used to extract metals economically. A large number of metals are present.
All Minerals are not ores.All ores are minerals.
Minerals are native forms in which metals exist.Ores are mineral deposits.

FAQs

1. What is the difference between minerals and ores?
Ans: Ore is the rock from which the metal is extracted in a convenient and economical way. Ore has a composition that is definite. Metals that occur naturally in the earth’s crust are called minerals. Minerals that can profitably be used to get the metal are called ores.

2. What are the different types of ores?
Ans: Ores are the minerals from which metal is conveniently and profitably extracted. There are mainly four kinds of ores like Ores Oxides; Ores Carbonate; Sulphide Ores; Ores Halides.

3. What is mineral ore used for?
Ans: Ore is a deposit of one or more precious minerals in the Earth’s crust. The most important ore deposits, such as copper, silver, and iron, contain metals that are essential to industry and trade. Copper ore is mined for a wide range of industrial applications. Copper, an exceptional electricity conductor, is used as an electrical wire.

4. What type of mineral is gold?
Ans: Gold has almost always traced of silver in its natural mineral form, and it can also contain traces of copper and iron.

5. What are the main ores of zinc?
Ans: Sphalerite (zinc blende), a mineral of zinc sulphide, is the most common zinc ore

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CLASS 6TH | THE RIVER VALLEY CIVILIZATION: EGYPTIAN, MESOPOTAMIAN AND CHINEASE CIVILIZATION | REVISION NOTES

MESOPOTAMIA

Mesopotamia was one of the earliest river valley civilization, starting to form around 4000 BCE. The civilization was created after regular trading started relationships between multiple cities and states around the Tigris and Euphrates Rivers. Mesopotamian cities became self-run civil governments. One of the cities within this civilization, Ur, was the first literate society in history. Eventually, they constructed irrigation systems to exploit the two rivers, transforming their dry land into an agriculturally productive area, allowing population growth throughout the cities and states within Mesopotamia.

Egypt

Ancient Egypt also created irrigation systems from its local river, the Nile River, more complex than previous systems. The Egyptians would rotate legumes with cereal which would stop salt buildup from the freshwater[clarification needed] and enhance the fertility of their fields. The Nile River also allowed easier travel, eventually resulting in the creation of two kingdoms in the north and south areas of the river until both were unified into one society by 3000 BCE.[7]

Yellow River

The Yellow River became settled in 9500 BCE. Many tribes settled along the river, sixth-longest in the world, which was distinguished by its heavy load of yellow silt and its periodic devastating floods. A major impetus for the tribes to unite into a single kingdom by around 1700 BCE (Erlitou culture, a Yellow River civilization) was the desire to find a solution to the frequent deadly floods. The Yellow River is often called “The Cradle of Chinese Civilization”.

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CLASS 6TH | THE RIVER VALLEY CIVILIZATION: INDUS VALLEY CIVILIZATION | REVISION NOTES

The story of Harappa

Harappa was one of the oldest cities in the subcontinent, which archaeologists found 80 years ago. This was the first city to be discovered. All other cities where buildings similar to Harappa were found, were described as Harappan.

What was special about Harappan cities?

These cities were divided into 2 or more parts.

  1. Citadel: The part to the west, which was smaller but higher was called the citadel.
  2. Lower town: The part to the east was larger but lower was called the lower town.

The walls of baked brick were built around each part. The bricks were so well baked that they have lasted for thousands of years. The bricks were laid in an interlocking pattern and that made the walls strong. In some cities, special buildings were constructed on the citadel. For example, in Mohenjodaro, a very special tank, which archaeologists call the Great Bath, was built in this area. Some cities like Mohenjodaro, Harappa, and Lothal had elaborate storehouses.

Houses, drains and streets

Most houses had a separate bathing area and some had wells to supply water. Many cities had covered drains. Each drain had a gentle slope so that water could flow through it. Drains in houses were connected to streets and smaller drains, which ultimately led into bigger ones. All three i.e.; houses, drains and streets were planned and built at the same time.

Life in the city

Harappan city was a very busy place.

  1. Rulers were the people who planned the construction of special buildings in the city. Rulers sent people to distant lands to get metal, precious stones, and other things that they wanted.
  2. Scribes were the people who knew how to write and help in preparing the seals and perhaps write on other materials that have not survived.
  3. There were men and women, crafts persons who used to make all kinds of things.
  4. Many terracotta toys have been found in Harappan cities, which shows that children must have played with these.

New crafts in the city

  1. Most of the objects that were made and found in Harappan cities were of stone, shell and metal, including copper, bronze, gold and silver.
  2. Copper and bronze were used to make tools, weapons, ornaments and vessels.
  3. Gold and silver were used to make ornaments and vessels.
  4. The Harappans made seals out of stone which were rectangular in shape and have an animal carved on them.
  5. The Harappans also made pots with beautiful black designs
  6. Actual pieces of cloth were found attached to the lid of a silver vase and some copper objects at Mohenjodaro.
  7. Archaeologists have also found spindle whorls, made of terracotta and faience, which were used to spin thread.
  8. Many of the things that were produced at Harappan were probably the work of specialists.

In search of raw materials

Raw materials are substances that are either found naturally or produced by farmers or herders. Raw materials are processed to produce finished goods. The raw materials that the Harappans used were available locally. Whereas many items such as copper, tin, gold, silver and precious stones were brought from distant places.

  1. The Harappans probably got copper from present-day Rajasthan, and from Oman in West Asia.
  2. Tin, which was mixed with copper to produce bronze, had been brought from present-day Afghanistan and Iran.
  3. Gold had been brought from present-day Karnataka, and precious stones from present-day Gujarat, Iran and Afghanistan.

Food for people in the cities

People living in the countryside grew crops and reared animals. The Harappans grew wheat, barley, pulses, peas, rice, sesame, linseed and mustard.

  1. The plough was used to dig the earth for turning the soil and planting seeds.
  2. Water was stored and supplied to the fields when the plants were growing.
  3. Harappans reared cattle, sheep, goat and buffalo. In the dry summer months large herds of animals were probably taken to greater distances in search of grass and water.
  4. People also collected fruits like ber, caught fish and hunted wild animals like the antelope.

A closer look – Harappan towns in Gujarat

The city of Dholavira was located on Khadir Beyt in the Rann of Kutch.

  1. This city has freshwater and fertile soil.
  2. Dholavira was divided into three parts, and each part was surrounded with massive stone walls, with entrances through gateways.
  3. There was also a large open area in the settlement, where public ceremonies were held.
  4. Large letters of the Harappan script were carved out of white stone and inlaid in wood.

The city of Lothal stood beside a tributary of the Sabarmati, in Gujarat, close to the Gulf of Khambat.

  1. The raw materials such as semi-precious stones were easily available in the city.
  2. There was also a store house in the city.
  3. Workshop for making beads: pieces of stone, half made beads, tools for bead making, and finished beads have all been found here.

The mystery of the end

Around 3900 years ago we find the beginning of a major change. People stopped living in many of the cities. Writing, seals and weights were no longer used. Raw materials brought from long distances became rare. In Mohenjodaro, we find that garbage piled up on the streets, the drainage system broke down, and new, less impressive houses were built, even over the streets.

Why did all this happen?

We are not sure. Some scholars suggest that the rivers dried up. Others suggest that there was deforestation. In some areas there were floods. But none of these reasons can explain the end of all the cities. It appears as if the rulers lost control. Sites in Sind and west Punjab (present-day Pakistan) were abandoned, while many people moved into newer, smaller settlements to the east and the south

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CLASS 6TH | URBAN LOCAL SELF-GOVERNMENT | REVISION NOTES

Summary

The urban local governments provide services to the people of their region.
The 3 types of local governments are :

  • Nagar Panchayat
  • Municipal Council
  • Municipal Corporation

Nagar Panchayat
The rural areas are fast developing into urban areas due the  population growth. The local government of these developing regions  are  called the ‘Nagar Panchayats’.

Municipal Council
Small cities are looked after by Municipal Councils. There are many Municipal Councils in every state which are also known as Nagar Committee or Nagar Sabha in different states. Members of a Municipal Council are called Councillors, they are elected by the voters of the area of the Municipal Council.

The complete area is divided into wards. One Councillor is elected from each ward. The MLAs falling in the area of that Municipal Council are also the members of the Municipal Council.

Functions of the Municipal Council

  • It provides public services such as electricity, water supply, cleanliness, maintenance of roads and bridges, schools, libraries and transport facilities.
  • It also prepares the statistics of birth and death registrations and helps open health centres and hospitals.

Municipal Corporations
In larger cities the institutions of local administration are called Municipal Corporation. If the Municipal Corporation is located in the capital of the country and in the union territories, then it is under the direct control of the Central Government.Members of the Municipal Corporation are directly elected by the voters of the city.

Municipal Corporations are divided into wards and one member is elected from each ward. The MLAs of a city are also the members of the Municipal Corporation. The Municipal Corporation performs both compulsory and discretionary functions.

The compulsory functions of Municipal Corporations
Construction and maintenance of roads and sewage system, supply of drinking water, health and sanitation, registration of births and deaths, and establishment of schools.

The discretionary functions of the Municipal Corporation
The establishment and maintenance of art galleries, museums, play parks and libraries.

Composition of  the Municipal Corporation
The Municipal Corporation consists of the Mayor, the Municipal Commissioner and the Committee.The Mayor is the head of the Municipal Corporation. He is elected from amongst the members of the Corporation and his term is two and a half years. The Municipal Commissioner, or the Chief Executive Officer, is appointed by the state government and belongs to the Indian Administrative Service (IAS).

Committees
Various committees, including the Standing Committee, Education Committee and Transport Committee, serve a term of two years. They carry out the activities of the Municipal Corporation. They utilise the funds from taxes such as house tax, entertainment tax and property tax. Fees from passing of house plans, fees from issuing licenses for cycles, rickshaws and carts, and penalties from violators of the Municipal Corporation rules also contribute to the funds and the Government also provides grants to the Corporation.

Elections
The election for all the levels of the urban local self government takes place every five years. There are reserved seats for women, scheduled castes and scheduled tribes in the urban local government. The urban local government is elected by the people and provides many services to them

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