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Free study notes for CBSE & ICSE, Classes 6–12.

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ScienceClass 10CBSE

Every Rule About Metals Has a Famous Exception

Compare metals and non-metals on lustre, malleability, ductility, conductivity, sonority and melting point, classify an unknown element from its stated properties, and name the six exceptions that break the rules.

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ScienceClass 10CBSE

Tooth Enamel Starts Dissolving Below a Certain pH

Read the pH scale and rank solutions by acidity, see why pH matters for teeth, digestion, soil and stings, work out whether a salt is acidic or basic from its parents, and learn the four important sodium and calcium compounds.

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ScienceClass 10CBSE

Phenolphthalein Stays Colourless Until a Base Arrives

Predict indicator colours for acids and bases, write the reactions of acids with metals, carbonates and hydrogencarbonates, name the salt from a neutralisation, and explain why an acid conducts only when dissolved in water.

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ScienceClass 10CBSE

Rusting Iron and Rancid Oil Are the Same Chemistry

Sort reactions into combination, decomposition, displacement and double displacement, tell the three kinds of decomposition apart by their energy source, label what is oxidised and reduced, and explain corrosion and rancidity.

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ScienceClass 10CBSE

A Chemical Equation Must Balance Because Atoms Cannot Vanish

Recognise from observation that a chemical reaction has taken place, turn a word equation into a balanced one with physical states, and balance a skeletal equation by hit and trial while checking that mass is conserved.

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MathematicsClass 9ICSE

One Right Triangle Hides Between Any Two Points

Derive the distance formula from the Pythagoras theorem, measure from the origin and the axes, prove points collinear or a triangle isosceles or right-angled, and find a missing coordinate or an equidistant point.

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MathematicsClass 9ICSE

Where Two Lines Cross Is the Answer to Both Equations

Draw two simultaneous equations on one pair of axes and read the solution from their crossing point, find where each line meets the axes, compute the area of the triangle they enclose, and check the answer algebraically.

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MathematicsClass 9ICSE

Every Straight Line Needs Only Two Points and a Ruler

Tell dependent from independent variables, plot points and name their quadrants, identify the figure formed by given vertices, and draw the graph of a linear equation from a table of values.

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MathematicsClass 9ICSE

Two Measurements Are Enough to Solve a Whole Triangle

Find every unknown side and angle of a right-angled triangle from two given parts, use standard angles to compute a length, solve pole and shadow problems, and pick the right triangle out of a larger figure.

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MathematicsClass 9ICSE

Sine and Cosine Are One Ratio Seen from the Other Corner

Use the complementary-angle relations to swap sine for cosine and tangent for cotangent, collapse expressions like sin 35 over cos 55 to a single number, and solve equations where a sine equals a cosine.

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MathematicsClass 9ICSE

Two Special Triangles Give Every Standard Angle Value

Derive the ratios of 0, 30, 45, 60 and 90 degrees from a square and an equilateral triangle, evaluate numerical expressions in them, verify given relations, and solve for a standard angle.

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MathematicsClass 9ICSE

Two Sides of a Triangle Hold All the Information About Its Angle

Write the six trigonometric ratios from a right-angled triangle, rebuild all six when only one is given, prove the basic identities from the Pythagoras theorem, and evaluate expressions from a single ratio.

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MathematicsClass 9ICSE

Volume Is Just a Cross-Section Dragged Along a Length

Find the volume and surface areas of cubes and cuboids, handle open boxes and painting costs, work out the material in a hollow box, and use cross-section times length for beams, pipes and canals.

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MathematicsClass 9ICSE

A Wheel's Circumference Is the Distance of One Full Turn

Find a circle's area and circumference either way round, compute the area of a ring, solve path-and-cost problems for rectangular and circular fields, and count the revolutions of a wheel.

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MathematicsClass 9ICSE

An Area from Three Sides Without Measuring Any Height

Find a triangle's area from its base and height or from its three sides, handle equilateral, isosceles and right-angled cases, compute areas of quadrilaterals, and split a composite figure into parts.

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MathematicsClass 9ICSE

One Wrong Entry Can Shift a Mean but Not a Median

Find the mean of raw data and of a frequency distribution, locate the median for an odd or even number of observations, and recover a missing value or correct a mean after a misread entry.

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MathematicsClass 9ICSE

Why Every Frequency Polygon Needs Two Extra Zeros

Tell raw, arrayed and grouped data apart, build a frequency table with tally marks, convert discontinuous class intervals into continuous ones, and draw a frequency polygon that closes properly.

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MathematicsClass 9ICSE

Three Points Not in a Line Decide Exactly One Circle

Show that exactly one circle passes through three non-collinear points and construct it, link equal central angles to equal arcs and equal chords, and solve riders on arcs, chords and angles.

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MathematicsClass 9ICSE

A Line from the Centre That Halves a Chord Must Be Perpendicular

Prove that a line from the centre bisecting a chord is perpendicular to it, find chord lengths and distances with the Pythagoras theorem, show equal chords are equidistant, and handle two parallel chords.

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MathematicsClass 9ICSE

Two Triangles Can Have the Same Area and No Common Shape

Prove that parallelograms on the same base between the same parallels are equal in area, that a triangle is half of one, and use equal areas to prove riders and to deduce equal altitudes.

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MathematicsClass 9ICSE

Six Steps of the Compass Round a Circle Give a Hexagon

Construct a quadrilateral from four sides and a diagonal, build a parallelogram from sides, diagonals and angles, draw a rhombus from its diagonals, and step off a regular hexagon with the compass alone.

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MathematicsClass 9ICSE

One Extra Condition Turns a Parallelogram into a Square

Prove that the diagonals of a rhombus meet at right angles and those of a rectangle are equal, name a quadrilateral from its stated properties, and solve trapezium riders with the mid-point theorem.

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MathematicsClass 9ICSE

The Diagonals of a Parallelogram Always Cut Each Other in Half

Prove that opposite angles of a parallelogram are equal and that its diagonals bisect each other, use the equal-and-parallel test to prove a figure is a parallelogram, and find unknown sides, angles and diagonal segments.

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MathematicsClass 9ICSE

Two Squares on the Legs Fill the Square on the Hypotenuse

Prove the Pythagoras theorem by comparing areas, find any missing side of a right-angled triangle, use the converse to test for a right angle, and solve ladder, pole, rhombus and diagonal problems.

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