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  • Chapter 5 Introduction to Euclid’s Geometry Notes for Class 9th Maths

    Chapter – 5 Introduction to Euclid’s Geometry

    1. Euclid’s Definitions, Axioms and Postulates
    2. Equivalent Versions of Euclid’s Fifth Postulate

    The Greeks developed geometry is a systematic manner Euclid (300 B.C.) a greek mathematician, father of geometry introduced the method of proving mathematical results by using deductive logical reasoning and the previously proved result. The Geometry of plane figure is known as “Euclidean Geometry”.

    Axioms: The basic facts which are taken for granted without proof are called axioms some Euclid’s axioms are:

    1. Things which are equal to the same thing are equal to one another. i.e. a = b, b = c ^ a = c
    2. If equals are added to equals, the wholes are equal i.e. a = b ^ a + c = b + c
    3. If equals are subtracted from equals, the remainders are equal i.e. a = b ^ a – c = b – c
    4. Things which coincide with one another are equal to one another.
    5. The whole is greater than the part.

    Postulates: Axioms are the general statements, postulates are the axioms relating to a particular field.

    Educlid’s five postulates are.

    1. A straight line may be drawn from any one point to any other point.
    2. A terminated line can be produced indefinitely.
    3. A circle can be drawn with any centre and any radius.
    4. All right angles are equal to one another.
    5. If a straight line falling on two straight lines makes the interior angles on the same side of it

    taken together less than two right angles, then the two straight lines, if produced indefinitely

    meet on that side on which the angles are less than two right angles.

    Statements: A sentence which is either true or false but not both, is called a statement. eg. (i) 4+9=6 If is a false sentence, so it is a statement.

    (ii) Sajnay is tall. This is not a statement because he may be tall for certain persons and may not be taller for others.

    Theorems: A statement that requires a proof is called a theorem. eg. (i) The sum of the angles of triangle is 180°.

    (ii) The angles opposite to equal sides of a triangles are equal.

    Corollary – Result deduced from a theorem is called its corollary.

  • Chapter 4 Linear Equations in Two Variables Notes for Class 9th Maths

    Chapter – 4 Linear Equations in Two Variables

    1. Linear Equations
    2. Solution of a Linear Equation
    3. Graph of a Linear Equation in Two Variables
    4. Equations of Lines Parallel to x-axis and y-axis
    • An equation of the form ax + by + c = 0 where a, b and c are real numbers such that a and b are not both zero is called a linear equation in two variables.
    • A pair of values of x and y which satisfy the equation ax + by + c = 0 is called a solution of the equation.
    • Graph: The graph of every linear equation in two variables is a straight line. Every point on the graph of a linear equation in two variables is two variables is a solution of the linear equation. Conversely, every solution of the linear equation is a point on the graph of the linear equation.
    • A linear equation in two variables has infinitely many solutions.
    • The graph of every linear equation in two variables is a straight line.
    • y = 0 is the equation of x-axis and x = 0 is equation of y-axis.
    • The graph of x = a is a straight line parallel to the y-axis.
    • The graph of y = a is a straight line parallel to the x-axis.
    • An equation of the type y = mx represent a line passing through the origin.

  • Chapter 3 Coordinate Geometry Notes for Class 9th Maths

    Chapter – 3 Coordinate Geometry

    1. Cartesian System
    2. Plotting a Point in the Plane with given Coordinates
    • Coordinate Geometry: The branch of mathematics in which geometric problems are solved

    through algebra by using the coordinate system is known as coordinate geometry.

    • Coordinate System: Coordinate axes: The position of a point in a plane is determined with

    reference to two fixed mutually perpendicular lines, called the coordinate axes.

    In this system, position of a point is described by ordered pair of two numbers.

    Ordered pair: A pair of numbers a and b listed in a specific order with ‘a’ at the first place and ‘b’ at the second place is called an ordered pair (a,b)

    Note that (a,b) ^ (b,a)

    Thus (2,3) is one ordered pair and (3,2) is another ordered pair.

    In given figure O is called origin.

    The horizontal line X1 OX is called the X-axis.

    The vertical line YOY’ is called the Y-axis.

    P(a,b) be any point in the plane. ‘a’ the first number denotes the distance of point from Y-axis and ‘b’ the second number denotes the distance of point from X-axis. a – X – coordinate | abscissa of P. b – Y – coordinate | ordinate of P.

    The coordinates of origin are (0,0)

    Every point on the x-axis is at a distance o unit from the X-axis. So its ordinate is 0.

    Every point on the y-axis is at a distance of unit from the Y-axis. So, its abscissa is 0.

    Note: Any point lying on X – axis or Y – axis Y-axis does not lie in any quadrant.

  • Chapter 2 Polynomials Notes for Class 9th Math

    CHAPTER – 2 POLYNOMIAL

    1. Polynomials in one Variable
    2. Zeroes of a Polynomial
    3. Remainder Theorem
    4. Factorisation of Polynomials
    5. Algebraic Identities
    • Constants: A symbol having a fixed numerical value is called a constant.
    • Variables: A symbol which may be assigned different numerical values is known as variable.
    • Algebraic expressions: A combination of constants and variables. Connected by some or all of the operations +, -, X and is known as algebraic expression.
    • Terms: The several parts of an algebraic expression separated by ‘+’ or ‘-‘ operations are called the terms of the expression.
    • Polynomials: An algebraic expression in which the variables involved have only nonnegative integral powers is called a polynomial.
    1. 5x2 – 4x2 – 6x – 3 is a polynomial in variable x.

    3

    1. (ii) 5 + 8x2 + 4x-2 is an expression but not a polynomial.

    Polynomials are denoted by p(x), q(x) and r(x)etc.

    • Coefficients: In the polynomial x3 + 3x2 + 3x +1, coefficient of x3, x2, x are1,3,3 respectively

    and we also say that +1 is the constant term in it.

    • Degree of a polynomial in one variable: In case of a polynomial in one variable the highest

    power of the variable is called the degree of the polynomial.

    • Classification of polynomials on the basis of degree.

    Degree Polynomial Example

    1. 1 Linear x +1, 2x + 3etc.
    2. 2 Quadratic ax2 + bx + c etc.
    3. 3 Cubic x3 + 3x2 +1 etc. etc.
    4. 4 Biquadratic x4 -1

    Classification of polynomials on the basis of no. of terms

    Polynomial & Examples. Monomial – S3Sx31Yetc.

    3

    No. of terms

    (i) 1

    Binomial – (3 + 6x), (x – 5y) etc.

    (ii) 2

    (iii) 3

    Trinomial- 2x2 + 4x + 2 etc. etc.

    • Constant polynomial: A polynomial containing one term only, consisting a constant term is called a constant polynomial the degree of non-zero constant polynomial is zero.
    • Zero polynomial: A polynomial consisting of one term, namely zero only is called a zero polynomial. The degree of zero polynomial is not defined.
    • Zeroes of a polynomial: Let p(x) be a polynomial. If p(a) =0, then we say that is a zero of the polynomial of p(x).
    • Remark: Finding the zeroes of polynomial p(x) means solving the equation p(x)=0.
    • Remainder theorem: Let f (x) be a polynomial of degree n > I and let a be any real

    number. When f(x) is divided by (x – a) then the remainder is f (a)

    • Factor theorem: Let f(x) be a polynomial of degree n > 1 and let a be any real number.
    1. If f (a) = 0 then (x – a) is factor of f (x)
    2. If (x – a) is factor of f (x)then f (a) = 0
    • Factor: A polynomial p(x) is called factor of q(x) divides q(x) exactly.
    • Factorization: To express a given polynomial as the product of polynomials each of degree less than that of the given polynomial such that no such a factor has a factor of lower degree, is called factorization.

  • Chapter 1 Number Systems Notes for Class 9th Maths

    CHAPTER – 1

    NUMBER SYSTEMS

    1. Rational Numbers
    2. Irrational Numbers
    3. Real Numbers and their Decimal Expansions
    4. Operations on Real Numbers
    5. Laws of Exponents for Real Numbers

  • Mathematics Notes Class 9th

    Notes in Of class 9th Mathematics Presented By ImperialStudy. With Step By Step Math Solution. If you are Getting Problem In Notes So, Here We Provide Full Notes Of Class IX Math Students Also We provide RD Sharam Solution Of Class 9th

    Notes for Class 9 – Maths

  • Improvement in Food Resources Notes Class 9th Science Chapter 15


    Chapter 15: “Improvement in food resources”

    KEY CONCEPTS : [ *rating as per the significance of concept]

    CONCEPTS RATING
    Improvement in crop yield ***
    Crop variety improvement ****
    Crop production management *****
    Crop protection management ***
    Animal Husbandry ****
    1. Food Resources: Cereals (Wheat, rice, maize, millets and sorghum) provide us carbohydrates; Pulses (Grams, pea and lentil) provide us proteins; Oil seeds (Soya bean, ground nut, sesame, and castor) provide us fats; Vegetables, spices and fruits provide us a range of minerals, nucleic acids and vitamins. In addition to these food crops, fodder crops like berseem, oats or sudan grass are raised as food for the livestock are called as fodder crops.
    2. The Kharif crops: The crops grown in rainy season are called as Kharif crops (Paddy, Soya bean, pigeon pea and maize). They are grown from June to October.
    3. The Rabi crops: The crops grown in winter season are called Rabi crops (Wheat, gram, peas, and mustard). They are grown November to April.

    Compare Kharif crops and Rabi crops:

    SN Crop Season Example
    1 Kharif crops June to October ( Rainy Season) Paddy, Soya bean, and maize
    2 Rabi crops November to April ( winter season) Wheat, gram, peas, and mustard
    1. The Green Revolution: Food supplies are generally as proteins, carbohydrates, fats, minerals, nucleic acids and vitamins in all living organisms. Indian population is growing enormously. Green Revolution is the need of the hour to increase food-grain production.
    2. Sustainable Practices: For sustained livelihood, one should undertake mixed farming, intercropping, and integrated farming practices, for example, combining agriculture with livestock/ poultry/ fisheries/bee-keeping. The major group of activities for improving crop yield can be classified as: Crop varietal improvement, Crop production improvement, Crop protection improvement
    3. The Crop varietal improvement:

    a) Hybridization: It refers to crossing between genetically dissimilar plants;It is all to get higher yield, improved quality, biotic and abiotic resistance, change in maturity duration, wider adaptability and desirable agronomic characteristics.

    SN Type Context
    1 Intervarietal Hybridization between different varieties
    2 Interspecific Hybridization between different species
    3 Intergeneric Hybridization between different genera
    4 Genetically Modified Crops (GMC). Another way of improving the crop is by introducing a gene that would provide the desired characteristic.
    1. The Crop production improvement: They include” no cost production”,” low cost production” or “high cost production” practices.
    2. Nutrients( Sixteen elements are required for growth are called as essential elements Carbon, oxygen, hydrogen+ Macronutrients & Micronutrients. They increase the yield):
    SN Macronutrient Micronutrient
    1 Six elements are required in larger quantity Other seven elements are required in small quantity
    2 Ex.Nitrogen, phosphorus, calsium,Postasium, magnisium, sulphur Ex. Iron, manganese, boron, zink, copper, molybdinum, chlorine
    1. Manure & Fertilizers:
    SN Manure Fertilizers
    1 Manure is prepared by the decomposition of animal excreta and plant waste is called as Humus. It decides the texture of the soil. Compost: Farm waste, cow dung etc. Vermi compost: Compost prepared by using earthworms. Fertilizers are commercially produced plant nutrients.

    Excess fertilizers destroy the soil fertility. Organic farming: No use of chemicals fertilizers, herbicides, pesticides etc.( Culturing blue green algae, neem leaves, healthy cropping systems.
    2 It is cheap and prepared in rural homes and fields It is costly and is prepared in factories
    3 It is voluminous and bulky It is compact and concentrated
    4 It is inconvenient to store, transport, handle. It is easy to store, transport, handle.
    5. It is not nutrient specific. It is nuteient specific and can provide specifically nitrogen, phosphorus etc.
    Add great humus to the soil Does not add humus to the soil.
    1. Irrigation: India has variety of water resources: Wells, canals, river lift system, tanks, rainwater harvesting, water shedding management to increase in ground water levels and to check the water flowing away to the sea. Planning to reduce soil erosion.

    4. Cropping patterns:

    SN Mixed cropping Inter-cropping Crop rotation
    1 Two or more crops grown simultaneously on the same piece of land Two or more crops grown simultaneously on the same piece of land in a definite pattern Growing different crops on a piece of land in a preplanned succession
    2 Ex. Wheat+ Gram; Wheat+ Mustard; Wheat+ gram; Groundnut+ sunflower. Soyabean + maize/bajra+Cowpea ((Please refer Fig. 15.2, NCERT Text Book Page- 208). Two or three crops can be grown in a year depending upon the duration.
    3 A type of insurance A few rows of one crop alternate The availability of
    against failure of one with a few rows of a second crop. moisture and
    of the crops. Crops are selected such that their irrigation facilities
    nutrient requirements are decides the choice
    different. This ensures the of the crop to be
    maximum utilization of the cultivated.
    nutrients supplied and prevents
    pests and diseases spreading in the
    crop field.

    8. Crop protection improvement/ management: Field crops are infested by large number

    of weeds, insects pests, diseases & storage of grains

    SN Weeds Insect pests Diseases Storage of grains
    1 Weeds are unwanted plants in the crop field Insect pest is nuisance in the crop field Disease is caused by pathogens in the field Different factors are responsible.
    2 Weeds take up nutrients and reduce the growth Insect pest affect the health of crop and reduce the yield. Diseases alter the physiology of crops and reduce the yield Different factors reduce the quality of stored grains
    3 Ex. Xanthium, Parthenium Ex. Caterpillars, dragonfly Ex. Bacteria, Virus Biotic factors: insects, rodents, fungi

    Abiotic factors: moisture & temperature
    4 Removal of weeds at an early stage is recommended. Spray weedicides Spread of chemicals such as pesticides Spread of chemicals to kill pathogens Systematic management of ware house.
    1. Animal Husbandry: It is a scientific management of animal livestock, includes feeding, breeding and diseases control. Animal-based farming includes cattle farming, Poultry

    farming, fish farming, and bee Keeping.

    SN Content Cattle

    farming

    		 Poultry

    farming

    		 Fish farming Bee Keeping.
    1 Purpose Milk (milch animals) and Meat,

    chicken, egg

    		 Cheep source of animal protein. Honey, wax, medicinal
    draught labor (draught animals) in agriculture. production Fish production is aquaculture. Growing of marine fishes is called

    mariculture.

    		 preparations. Additional income to the farmer.
    2 Cross

    breeding: To get desired qualities

    		 Exotic- quality of lactation Indigenous breeds- quality of disease resistance Exotic &

    Indigenous

    breeds

    		 Both Exotic & Indigenous fishes are used Exotic- high honey collection capacity &stingless. Indigenous bees- are used
    3 Desirable

    maintenance

    		 Good

    ventilation in

    sheds

    Roughage/

    concentrates

    Protection

    from

    parasites & skin diseases Vaccination

    		 Good

    ventilation in

    sheds

    Roughage/

    concentrates

    Protection

    from

    parasites & skin diseases Vaccination

    		 Fish farming/ locating large schools of fish/ use of satellites and echo-sounds In Composite fish culture seed is wild, mixed with other species. Hormonal stimulation to bring desired quality in fish production. Value or quality depends upon the pasturage or the flowers available for the taste of honey.
    4 Example Exotic or foreign breeds ( Jercy, brown Swiss)

    Local breeds (Red sindhi, Sahiwal)

    		 Exotic- Leghorn Indigenous breeds- Aseel Fresh water ( Macrobrachium) & Marine( Peneaus) prawns Fresh water fishes

    Marine fishes( Bombay duck, sardines) Common

    		 Apisceranaindica

    dorsata

    A.florae

    QUESTION BANK

    1. Give two examples of Cereals (Wheat, rice)
    2. Define the Kharif crop and give two examples fThe crops grown in rainy season are called as Kharif crops Ex. Paddy, Soya bean).
    3. Write about the importance of Green Revolution (Indian population is growing enormously. Green Revolution is the need of the hour to increase food-grain production.
    4. Define the term Hybridization(Crossing between genetically dissimilar plants)
    5. What is the importance of Genetically Modified Crops? (It is another way of improving the crop is by introducing a gene that would provide the desired characteristic.)
    6. Define the term mixed cropping and give two examples. (Two or more crops grown simultaneously on the same piece of landEx. Wheat+ Gram; Wheat+ Mustard)
    7. Distinguish between weeds, insects pests(Weeds are unwanted plants in the crop field Insect pest is nuisance in the crop field)
    8. What is Animal Husbandry? It is a scientific management of animal livestock, includes feeding, breeding and diseases control. Animal-based farming includes cattle farming, Poultry farming, fish farming, and bee keeping.
    9. Distinguish between aquaculture and mariculture. (Fish production is aquaculture. Growing of marine fishes is called mariculture.)
    10. What is the importance of Bee Culture? (It is useful for honey, wax, medicinal preparations. And also for additional income to the farmer.)

    QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

    Marks- 40 Time: 90 minutes

    * General Instructions

    1. Questions 1-5 (1 Mark each) 2. Questions 6-10 (2 Mark each)

    1. Questions 11-15 (3Mark each) 4. . Questions 16-17 (5Mark each)

    Q.1 Maize and Millets are Pulses. Mention True/False

    Q.2 What is the Scientific name of Honey Bee

    Q.2 What led us to improve food grain production?

    Q.3 Which revolution led to the availability of milk for efficient use?

    Q.4 What is the process of injecting semen of desired bull into the vagina of cows is called? Q.5 Name any one exotic breed usually used for variety of improvement programmes.

    Q.6 What is the significance of GMC

    Q.7 Mention the significance of Irrigation in developing agriculture.

    Q.8. What is Pest and give one example.

    Q.9 What is Weed and give one example.

    Q.10 Give two examples for Inter-cropping.

    Q.11 Distinguish between Kharif and Rabi Crops

    Q.12 What is called Sustainable Practice in improvement in food resources.

    Q.13. Mention three techniques of Hybridization used to achieve desirable agronomic characteristics.

    Q.14.Distinguish between Macro Nutrients and Micro Nutrients Q.15 Distinguish between Compost and Vermi Compost.

    Q.16 Distinguish between Cattle farming and Poultry farming.

    Q.17 Distinguish between Fish farming and Bee keeping.

  • Natural Resources Notes Class 9th Science Chapter 14


    Chapter 14: “Natural resources”

    KEY CONCEPTS : [ *rating as per the significance of concept]

    CONCEPTS RATING
    Breath of air **
    A wonder liquid ***
    Biogeochemical cycles *****
    1. The” Biosphere” is the life supporting zone of the earthwith three sub-zones called as lithosphere (rock part), atmosphere (air part)and hydrosphere (water part).

    Breath of air

    1. Composition of Air

    1. The interactions between different components of the Biosphere to maintain the balance between the biotic and a biotic component makes “Biogeochemical cycle”. Ex. Water Cycle, Nitrogen Cycle, Carbon cycle, Oxygen Cycle,
    2. Role of atmosphere in climate control : atmosphere act as protective blanket for the earth. Since atmosphere is a bad conductor of heat, it keeps the average temperature of the earth constant. At night, it slows down the escape of heat into outer space.
    3. The movement of air : the atmosphere gets heated from the radiation that is reflected back by the land or water bodies. As a result of heating, convection currents are set up in the air. Since land gets heated faster than water, the air over land gets heated faster than air above water bodies.
    4. In coastal regions, during the day, the air above the land gets heated faster and starts rising. So a region of low pressure is created and air over sea moves into this area of low pressure. The movement of air from one region to the other region causes Wind.
    5. During the day, the direction of wind would be from the sea to the land and at night, both land and sea starts to cool. Since water cools down slower than the land, the air above water would be warmer than air above land, thus the direction of wind would be from the land to the sea.
    6. Air pollution : it is an undesirable change in the physical, chemical or biological characteristics. It is caused due to an increase in the content of harmful substances (pollutant) such as oxides of nitrogen and sulphur, etc.

    7. Harmful effect of air pollution :
    • It affects the respiratory system causing breathing difficulties eg; bronchitis, asthma, lung cancer, tuberculosis, etc.
    • Burning of fossil fuels like coal and petroleum releases oxides of nitrogen and sulphur. Inhalation of these gases is dangerous.
    • Combustion of fossil fuel also increases the amount of suspended particles in air. The presence of high levels of all these pollutants, reduce visibility in cold weather where water also condenses out of air forming smog.
    • Acid rain formed from the gases like sulphur dioxide and nitrogen oxides present in polluted air. It causes damage to living and non- living thing.

    1. The Water Cycle:
    2. The process in which water evaporates and falls on the land as rain and later flows back into the sea via rivers is known as the “Water Cycle”. Water flows through rocks containing soluble minerals, some of them get dissolved in the water. Thus the rivers carry many nutrients from the land to sea and these are used by the marine organisms.
    3. When the water vapors condense as water droplets and grow big and heavy, they fall down in the form of “rain”. It ranges from 5 cm to 200 cm of rain fall in a year in our country. In large parts of India, rains are mostly brought by the south-west or north-east monsoons. Depressions in the Bay of Bengal may also cause rains in some areas.
    4. Water is a wonder liquid because all cellular processes take place in a water medium; substances are transported in a dissolved form; terrestrial forms require fresh water to maintain the equilibrium of salts; major resource to determine the life on the earth.
    5. The dissolved fertilizers (NPK fertilizers), pesticides (DDT), sewage (Disease causing Organisms), waste from factories (Mercury) and water released from the dams can affect the life forms on the earth. The dissolved Oxygen is being used by the animals and plants that live in water, would adversely affect the aquatic organisms. The change in temperature would be dangerous for the eggs and larvae of the various animals particularly susceptible to temperature changes. It leads to “water pollution”.

    (Please refer Fig. 14.5, NCERT Text Book Page-197).

    1. Nitrogen Cycle:
    2. The nitrogen gas makes up 78% of our atmosphere. It is essential for the synthesis of proteins, DNA, RNA, urea, alkaloids and Vitamins.
    3. The simple molecular nitrogen from the atmosphere is converted into more complex molecules in the living beings and back again to atmosphere is called “Nitrogen Cycle”.
    4. Nitrogen fixation by Lightening: During lightning, the molecular nitrogen is converted into oxides of nitrogen and dissolves in water to give nitric and nitrous acids and fall on lands along with rains. These are then utilized by various life forms.
    5. Nitrogen fixation by Bacteria: The molecular nitrogen is converted into nitrates and nitrites, by free living bacteria or the bacteria present in the root nodules of legumes.
    6. The conversion of molecular nitrogen into nitrates and nitrites is called as” Nitrification”. Plants generally covert them into amino acids. The conversion of nitrates and nitrates into Ammonia is called as” Ammonification”. The conversion of Ammonia into molecular Nitrogen is called as” Denitrification”. Thereby nitrates and nitrites are converted into molecular or elemental nitrogen in the nature. (Please refer Fig. 14.6, NCERT Text Book Page- 198).
    7. The Carbon cycle:
    8. The Carbon dioxide gas makes up 0.039 % of our atmosphere. Carbon occurs in the elemental form as diamonds and graphite in earth. Carbon is essential for the synthesis of proteins, carbohydrates, fats, nucleic acids and Vitamins in living organisms.
    9. The Carbon dioxide Fixation: Green plants convert Carbon dioxide into glucose in the presence of sunlight through Photosynthesis. The glucose molecules are converted into other biologically important molecules. And many marine animals use carbonates dissolved in sea water to make shells, exoskeletons.
    10. The combustion: The Carbon dioxide in the atmosphere is added by the process of combustion, where fuels are burnt to provide energy for various needs like heating, cooking, transportation, and industrial process.
    11. The Greenhouse Effect: The percentage of Carbon dioxide in the atmosphere is said to have doubled since the industrial revolution when human beings stated burning fossil fuels on a very large scale. The Carbon dioxide is a greenhouse gas. The increase in the Carbon dioxide content would cause more heat to be retained by the atmosphere and lead to Global Warming. It is called” Greenhouse Effect”
    12. The carbon cycle is repeated through different physical and biological activities. (Please refer Fig. 14.7, NCERT Text Book Page- 199).

    6 .Oxygen Cycle:

    1. The Oxygen gas makes up 21 % of our atmosphere. Oxygen is essential component of proteins, carbohydrates, fats, nucleic acids in living organisms.
    2. Oxygen from our atmosphere is used up in three processes, namely combustion, respiration and in the formation of oxides of nitrogen. Oxygen is returned to the atmosphere in only one major process, that is, Photosynthesis, it is called as Oxygen Cycle.
    3. The air is heated faster than water; the air over land would also be heated faster than the air over water bodies. The movement of air from one region to the other creates winds, during the day the direction of the wind would be from the sea to land. At night, both land and sea start to cool.
    4. The oxides of nitrogen and sulphur gases dissolve in rain to gives rise to “Acid rains”. The smog is a visible indication of Air Pollution. The pollutants bring respiratory, cardiac problems and allergies. The organisms called Lichens are found on the bark of trees, they are indicators of pollution free environment. Three atoms of Oxygen ( O3) is called as Ozone. The Ozone is poisonous but absorbs harmful radiations from the Sun. The Ozone layer around the earth, if, dwindles further may cause Health hazards including Cancers . Recently discovered the Ozone hole; in the region of Antarctica. (Please refer Fig. 14.8 & 14.9, NCERT Text Book Page- 200).


    QUESTION BANK

    1. What are the three sub-zones in the Biosphere? {Lithosphere (rock part), atmosphere (air part)and hydrosphere (water part)}.
    2. The process in which water evaporates and falls on the land as rain and later flows

    back into the sea via rivers is known (Water Cycle).

    1. In large parts of India, rains are mostly brought by monsoons.( the south

    west or north-east monsoons).

    1. Why water is a wonder liquid? Justify ( A major resource to determine life on the earth)
    2. What are the four major water Pollutants?{ (NPK fertilizers, pesticides (DDT), sewage (Disease causing Organisms), waste from factories (Mercury)}
    3. Write a short notes on Nitrogen fixation by Bacteria.{The molecular nitrogen is converted into nitrates and nitrites, by free living bacteria or the bacteria present in the root nodules of legumes}.
    4. What is Greenhouse Effect? {The Carbon dioxide is a greenhouse gas. The increase in the Carbon dioxide content would cause more heat to be retained by the atmosphere and lead to Global Warming. It is called” Greenhouse Effect”}
    5. What is the percentage of Oxygen gas in our atmosphere? {21 %}
    6. Which organisms are found on the bark of trees as indicators of pollution free environment? { Lichens}
    7. Write about the Ozone hole in the Antarctica. {The Ozone layer around the earth is dwindling further to damage and cause Health hazards including Cancers. Recently discovered Ozone hole in the Antarctica.}

    QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

    Marks- 40 Time: 90 minutes

    • General Instructions

    1. Questions 1-5 (1 Mark each) 2. Questions 6-10 ( 2 Mark each)

    1. Questions 11-15 (3Mark each) 4. . Questions 16-17 (5Mark each)

    Q.1 What is called Lithosphere, define it.

    Q.2 Water covers 75% of the Earth’s surface. Mention True/ false

    Q.3 What is the percentage of Carbon dioxide on Venus

    Q.4 What is the range of temperature on the Moon

    Q.5 Define the term Pollutant

    Q.6 What are the two ways to fix Carbon dioxide on earth.

    Q.7 Mention any two important features of Water.

    Q.8 How the Depressions effect our environment?

    Q.9 Define the term Soil Pollution. Give one reason for it.

    Q.10 How changes of temperature effect living organisms in water?

    Q.11 What is Humus? Mention its importance in two points.

    Q12 What is deforestation? Give two reasons for it.

    Q.13. Define Global Warming, mention two causes for it.

    Q.14 What is Ozone Depletion? Give two reasons for it.

    Q.15 Draw the schematic diagram of Water Cycle in the nature.

    Q.16. Write any five salient features of Nitrogen Cycle with a suitable diagram.

    Q.17 Write about Industrial Pollution and mention five effects in the environment.

  • Why Do We Fall Ill Notes Class 9th Science Chapter 13

    Chapter 13: “Why do we fall ill?”

    KEY CONCEPTS : [ *rating as per the significance of concept]

    CONCEPTS

    RATING

    Significance of Health

    **

    Disease and Its causes

    ***

    Infectious diseases

    *****

    Principles of prevention of diseases

    ****

    !.”Health” is a state of being well enough to function well physically, mentally, and socially.

    1. “Disease”( disturbed ease) means being uncomfortable. One or more systems of the body will change, give rise to “Symptoms” ( Cough, loose motions, pus formation, headache, fever, breathlessness, vomiting, fits, unconsciousness, inflammation , swelling and general effects – a Doctor look for the basis of symptoms). Diseases are basically two types- Acute Disease & Chronic Disease
    2. Acute Disease: The disease which lasts for only a short period of time is called Acute Disease Ex. Common Cold.
    3. Chronic Disease: The disease which lasts for long period of time is called Chronic Disease Ex. Tuberculosis.

    Acute Disease

    Chronic Disease

    They are short duration disease

    They are long lasting disease

    Patient recovers completely after the cure

    Patient does not recover completely

    There is no loss of weight or feeling of tiredness afterward

    There is often loss of weight of feeling of tiredness

    There is short duration loss of work and efficiency

    There is a prolonged loss of work and efficiency

    1. Causes of Diseases : Most of the diseases have many causes, rather than one single cause, like unclean water, nourishment, genetic differences, genetic abnormalities e.g. Based on the causes diseases are of two types: Non-Infectious Diseases and Infectious Diseases.
    2. Non-Infectious Diseases: Not caused by infectious agents, mostly internal and non- infectious cause. Ex. Cancer
    3. Infectious Diseases: Caused by infectious agents.

    SN

    Type Of Disease

    Example

    1

    Bacterial diseases

    – Typhoid, Cholera, Tuberculosis, Acne, Anthrax,

    2

    Viral diseases

    – Common Cold, Influenza, Dengue fever, AIDS, Japanese encephalitis or brain fever

    3

    Fungal diseases

    Skin diseases

    4

    Protozoan diseases

    -Malaria ( Plasmodium), Kalaazar (Leishmania), Sleeping sickness( Trypanosomes)

    5

    Worm diseases

    – Ascariosis ( Round worm), Elephantiasis(Wuchereria )

    (Please refer Fig. 13.1 (a-e), NCERT Text Book Page-181).

    a)The infectious diseases spread by agents are called as Communicable Diseases.

    SN

    Type of Disease

    Example

    1

    Air born Diseases

    – Pneumonia, common cold, Tuberculosis;

    2

    Water born diseases

    – Cholera, hepatitis

    3

    Sexual Diseases

    – HIV, Syphilis.

    4

    Animal born Disease

    – Rabbis.

    *(Vector- the animal carrying infectious agent from a sick person to another potential host without getting affected Ex. Mosquito carrying Malaria Parasite).

    (Please refer Fig. 13.2 & 13.3, NCERT Text Book Page- 183).

    1. Principles of Treatment:
    2. Antibiotics- many bacteria make a cell wall to protect themselves, the antibiotic (Penicillin) blocks the bacterial process that builds cell wall and blocks the biochemical pathways. Antibiotics do not work against viral infections. Antiviral medicine is harder than making Antibacterial medicine because Virus has only few biochemical mechanisms of their own. Other medicines bring down fever, reduce pain or loose motions. We can take bed rest to conserve energy.

    10 Principles of Prevention : Following three limitation are normally confronted while treating an infectious disease:

    • Once someone has disease, their body functions are damaged and may never recover completely.
    • Treatment will take time, which means that someone suffering from a disease is likely to be bedridden for some time even if we can give proper treatment.
    • The person suffering from an infectious disease can serve as the source from where the infection may spread to other people.

    General ways of preventing infectious disease :

    • Air-borne – We can prevent exposure by providing living condition that are not overcrowded.
    • Water-borne – prevent by providing safe drinking water. This is done by treating the water to kill any microbial contamination.
    • Vector-borne – We can provide clean environment, which would not allow mosquito breeding.
    1. Immunity: Even in cells there is repair mechanism called” Immunity”. Immune cells manage to kill off the infectious agents. Smallpox disease is eliminated by developing memory cells for particular infection by mimics the microbes, called” Vaccine”. The basis of Immunization- if you had smallpox once, there was no chance of suffering from it again. Proper nutrition is essential to maintain body immunity. There are vaccines against tetanus, diphtheria, whooping cough, measles, polio and many other diseases.
    2. Prevention of disease is better than cure. Hygiene is the basic key to maintain good health.

    QUESTION BANK:

    1. Define Health (It is astate of being well enough to function well physically, mentally,

    and socially)

    1. Name any two Symptoms of diseases (Cough& loose motions)
    2. The disease which last for only a short period of time is called ( Acute Disease)
    3. State whether Tuberculosis is aChronic Disease or Acute Disease (Chronic Disease)
    4. Mention the causal organism for Sleeping sickness (Trypanosoma)
    5. Cholera is a waterborne disease, mention TRUE/ FALSE (TRUE)
    6. Antibiotics do not work against viral infections, mention TRUE/ FALSE (TRUE)
    7. Write short notes on Immunity

    (Even in cells there is repair mechanism called” Immunity”. Immune cells manage to kill off the infectious agents.)

    1. Explain with an example the term Vaccine. ( Smallpox disease is eliminated by developing memory cells for particular infection by mimics the microbes, called” Vaccine”).
    2. State reasons to support “Prevention of disease is better than cure”.

    QUESTION PAPER:FORMATIVE ASSESSMENT – I (For Practice)

    Marks- 40 Time: 90 minutes

    • General Instructions

    1. Questions 1-5 (1 Mark each) 2. Questions 6-10 ( 2 Mark each)

    1. Questions 11-15 (3Mark each) 4. . Questions 16-17 (5Mark each)

    Q.1 Define Health

    Q.2 Mention any two symptoms of diseases.

    Q.3 Typhoid is a bacterial disease. Mention True/ False

    Q.4 Sleeping sickness is caused by

    Q.5 Elephantiasis is caused by

    Q.6. Mention two Air born diseasesl 2

    Q.7 Mention two Sexually Transmitted Diseaesl 2

    Q.8 Mention two Viral Diseaesl 2

    Q.9 What is called vector. Give one example.

    Q.10 Give two examples of Chronic diseases.

    Q.11 Distinguish between Infectious and Non-infectious diseases.

    Q.12 Write a short notes on Small Pox.

    Q.13 What is immunity? Write short notes on it.

    Q.14 What is Vaccination? Give the details, how it works in human body.

    Q.15 Write three reasons for Cancers.

    Q.16 What are the basic five principles of treatment for diseases.

    Q.17 How Hygiene could help you to maintain good health and mention five situations to take care about health.

  • Sound Notes Class 9th Science Chapter 12


    CHAPTER 12 – “Sound”

    KEY CONCEPTS [ *rating as per the significance of concept]

    1 Production of Sound ****
    2 Propagation of Sound *****
    3 Reflection of Sound *****
    4 Echo ****
    5 Uses Of Multiple Reflection Of Sound ***
    6 Range of Hearing ***
    7 Applications of Ultrasound **
    8 SONAR **
    9 Structure of Human Ear ****

    1. Production of Sound

    Sound is produced due to the vibration of objects. Vibration is the rapid to and fro motion of an object.

    Vibrating objects are the source of all sounds Irregular, chaotic vibrations produce noise Regular, controlled vibration can produce music All sound is a combination of pure frequencies A stretched rubber band when plucked vibrates and produces sound.


    1. Propagation of Sound

    When an object vibrates, the particles around the medium vibrate. The particle in contact with the vibrating object is first displaced from its equilibrium position

    The disturbance produced by the vibrating body travels through the medium but the particles do not move forward themselves.

    A wave is a disturbance which moves through a medium by the vibration of the particles of the medium. So sound is considered as a wave.Sound waves Require medium for transmission.Sound waves are called mechanical waves. When a vibrating object moves forward, it pushes and compresses the air in front of it forming a region of high pressure called compression (C). When the vibrating object moves backward, it forms a region of low pressure called rarefaction (R).


    Sound is longitudinal wave motion

    A vibrating object producing a series of compressions (C) and rarefaction (R)

    In these waves the particles move back and forth parallel to the direction of propagation of the disturbance. Such waves are called longitudinal waves.

    There is another kind of waves called transverse waves. In these waves the particles oscillate up and down perpendicular to the propagation of the direction of disturbance.

    Sound propagates in a medium as a series of compressions (C) and rarefactions (R).

    Compressions are the regions of high pressure and density where the particles are crowded and are represented by the upper portion of the curve called crest.

    Rarefactions are the regions of low pressure and density where the particles are spread out and are represented by the lower portion of the curve called trough Characteristics of a sound wave


    Frequency of sound wave

    The number of oscillations per unit time is called the frequency of the sound wave. It is represented by the symbol V (Greek letter nu). Its SI unit is hertz (Hz)

    Time period of sound wave

    Frequency and time are represented as follows:- V for one oscillation 1 1

    T = — or V = —

    V T

    Amplitude of sound wave

    The amplitude of sound wave is the height of the crest or tough. It is represented by the letter A.

    The SI unit is the same as that of density or pressure.


    Wavelength and Amplitude

    The wavelength is the distance between the “crests” of two waves that are next to each other. The amplitude is how high the crests are.


    Pitch and loudness of sound

    The pitch of sound (shrillness or flatness) depends on the frequency of vibration.

    If the frequency is high, the sound has high pitch and if the frequency is low, the sound has low pitch Speed of sound

    The speed of sound is more in solids, less in liquids and least in gases.

    The speed of sound also depends on the temperature of the medium. If the temperature of the medium is more, the speed of sound is more


    1. Reflection of Sound

    Sound gets reflected at the surface of a solid or liquid and follows the laws of reflection.

    1. The angle of incidence is equal to the angle of reflection.
    2. The incident ray, the reflected ray and normal at the point of incidence all lie in the same plane.


    Plate

    o

    ► Screen

    Renection of sound from a plane surface


    4. Echo

    If we shout or clap near a reflecting surface like tall building or a mountain, we hear the same sound again. This sound which we hear is called echo. It is caused due to the reflection of sound.

    To hear an echo clearly, the time interval between the original sound and the echo must be at least 0.1 s.

    Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344 m/s x 0.1 s = 34.4 m

    So to hear an echo clearly, the minimum distance of the reflecting surface should be half this distance that is 17.2 m.


    Reverberation

    Echoes may be heard more than once due to repeated or multiple reflections of sound from several reflecting surfaces. This causes persistence of sound called reverberation.

    In big halls or auditoriums to reduce reverberation, the roofs and walls are covered by sound absorbing materials like compressed fibre boards, rough plaster or draperies.


    1. Uses Of Multiple Reflection Of Sound

    Megaphones, horns, musical instruments like trumpets, etc. are deigned to send sound by multiple reflection in a particular direction without spreading in all directions.

    1. Doctors listen to sounds from the human body through a stethoscope. The sound of heartbeat reaches the doctor’s ears by multiple reflection.
    2. Generally the ceilings of cinema halls and auditoriums are curved so that sound after multiple reflection reaches all parts of the hall.

    Sometimes a curved sound board is placed behind the stage so that sound after multiple reflection spreads evenly across the hall.


    1. Range of Hearing

    Human beings can hear sound frequencies between 20 Hz and 2000 Hz.

    Sound whose frequency is less than 20 Hz is called infrasonic sound Sound whose frequency is more than 2000 Hz is called ultrasonic sound

    1. _Uses of ultrasonic sound

    Ultrasonic sound is used to clean objects like electronic Components, used to detect cracks in metal blocks, used in ultra sound scanners for getting images of internal organs of the human body used to break small stones formed in the kidneys into fine grains.


    8 Sonar

    It is a device which uses ultrasonic waves to measure distance, direction and speed of underwater objects. The distance of the object can be calculated by knowing the speed of sound in water and the time taken between the transmission and reception of ultrasound


    The sound waves passes through the ear canal to a thin membrane called eardrum. The eardrum vibrates. The vibrations are amplified by the three bones of the middle ear called

    hammer, anvil and stirrup. Middle ear then transmits the sound waves to the inner ear. The brain then interprets the signals as sound.

    QUESTION BANK

    One mark questions

    1. What do you understand by sound waves?
    2. Give an example to show that sound travels at a finite speed.
    3. Is sound wave longitudinal or transfer.
    4. Name two quantities that vary periodically at a place in air as a sound wave travels through it .
    5. An airplane produces a sound wave with frequency of 5 KHz and wavelength 30 m. In how much time would the sound wave cover the distance of 4 Km?
    6. With the help of a diagram show how longitudinal waves like sound waves travel in air.
    7. With the help of a diagram show how longitudinal waves like sound waves travel in air.
    8. Can we hear the ringing of a mobile phone placed in a vacuum chamber?
    9. Can two astronauts talk on moon a they does on the surface of the earth?

    Two marks questions

    1. Explain how echoes are used by bats to judge the distance of an obstacle?
    2. State the special properties of ultrasound that make it useful to us .In general, how these properties are utilized.
    3. Why is soft furnishing avoided in concert halls?
    4. Draw a diagram depicting low pitched sound and high pitched sound and write main difference between the two?
    5. Distinguish between longitudinal and transverse waves. Give one example each.
    6. An explosion takes place at the moon. After what time would it be heard at the earth?

    Three marks questions

    1. Two sources A and B vibrate with the same amplitude. They produce sounds of frequencies 1 kHz and 30 kHz respectively. Which of the two waves will have greater power?
    2. Find the time period of the source of a sound wave whose frequency is 400Hz.
    3. A sound wave travels at a speed of 340m/s. If its wavelength is 2 cm, what is the frequency of the wave? Will it be in the audible range?
    4. The grandparents and parents of a two year girl are playing with her in a room. A sound source produces a 28—kHzsound.who in the room is most likely to hear the sound?

    Five marks questions

    1. Sound cannot travel in vacuum. Describe an experiment to demonstrate this.
    2. With the help of a diagram describe how compression and rarefaction pulses are produced in air near a source of sound.
    3. Explain briefly how a flaw in a mental component can be detected using ultrasound?
    4. Explain the working and application of SONAR.
    5. A monkey drops a coconut from the top of a tree. He hears the sound of the coconut hitting the ground 2.057 seconds after dropping it .If the monkey was 19.6 metres above the ground, what is the speed of sound in air?(take g = 9.8m/s2).
    6. Draw a neat diagram of human ear. Explain the function of various parts. What have you learnt

    Longitudinal waves: Those in which the direction of vibration is the same as their direction of propagation. So the movement of the particles of the medium is either in the same or in the opposite direction to the motion of the wave. Exemple: sound waves, what changes in this case is the pressure of the medium (air, water or whatever it be).

    Transverse waves: The oscillations occur perpendicularly to the direction of energy transfer. Exemple: a wave in a tense string. Here the varying magnitude is the distance from the equilibrium horizontal position

    A general property of waves is that their speed relative to medium depends on the properties of medium but is independent of the motion of the source of waves. If the observer is in motion with respect to the medium, the velocity of wave propagation relative to the observer wil be different. A remarkable exception is encountered in the case of light PROPERTIES Frequency

    • Wavelength
    • Period
    • Amplitude
    • Intensity
    • Speed
    • Direction Perception of Sound

    For humans, hearing is limited to frequencies between about 20 Hz and 20000 Hz, with the upper limit generally decreasing with age.

    KEY LEARNING:

    Vibration – repetitive back and forth motion Periodic motion – a motion that repeats itself Mechanical waves require medium for propagation Waves move through medium but medium remains in place

    Longitudinal waves-Vibration direction parallel to wave propagation direction Particles in medium move closer together/farther apart .Example: sound waves Gases and liquids – support only longitudinal waves Transverse waves-

    Vibration direction perpendicular to wave propagation direction .Example: plucked string Solids – support both longitudinal and transverse waves Sound waves Require medium for transmission

    1. Sound is a wave motion, produced by a vibrating source.
    2. A medium is necessary for the propagation of sound waves.
    3. Sound is a longitudinal wave in which the particles of medium move along the direction of motion of wave.
    4. The part or region of a longitudinal wave in which the density of the particles of the medium is higher than the normal density is known as compression.
    5. The part or region of a longitudinal wave in which the density of the particles of the medium is lesser than the normal density is called a rarefaction.
    6. The point of maximum positive displacement on a transverse wave is known as crest.
    7. The point of maximum negative displacement on a transverse wave is known as through.
    8. A wave or short duration which is confined to a small portion of a medium at any given time is known as a pulse.
    9. The maximum displacement of particles of the medium from their mean positions during the propagation of a wave is known as amplitude of the wave.
    10. The distance traveled by a wave in one second is called wave velocity. It depends upon the nature of the medium through which it passes.
    11. The speed of sound depends primarily on the nature and the temperature of the transmitting medium.
    12. Sound travels faster in solids than in air. The speed of sound in solids is much more than the speed of sound in liquids or gases.
    13. The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength.
    14. Frequency is defined as the number of oscillations per second.
    15. The time taken by the wave for one complete oscillation of the density or pressure of the medium is called the time period, T.
    16. How the brain interprets the frequency of an emitted sound is called the pitch of sound.
    17. Loudness is the degree of sensation of sound produced.
    18. Sound properties such as pitch, loudness and quality are determined by the corresponding wave properties.
    19. Sound gets reflected and follows the same law as the reflection of light.
    20. The persistence of sound due to repeated reflection and its gradual fading away is called reverberation of sound.
    21. Echo is a repetition of sound due to the reflection of original sound by a large and hard obstacle.
    22. The audible range of hearing for average human beings is in the frequency range of 20 Hz – 20 kHz.
    23. The amount of sound energy passing each second through unit area is called the intensity of sound.
    24. Sound of frequency less than 20 Hz is known as infrasound and greater than 20 kHz is known as ultrasound.
    25. Ultrasound has many medical and industrial applications.
    26. SONAR stands for Sound Navigation and Ranging and it works on the principle of reflection of sound waves.
    27. The SONAR technique is used to determine the depth of the sea and to locate under water hills, valleys, submarines, icebergs sunken ships etc.