1. Why are people considered an important part of society?

People are considered an important part of society as they develop the economy and the society, make and use resources. People are both producers and consumers of the resources.

1. What is climate?

Climate refers to sum total of weather conditions over a large area for a long period of time (30 - 40 years).

1. What is a river/drainage basin?

A river/drainage basin is an area drained by a single river system.

It is difficult for us to imagine a world without printed matter. We find evidence of print everywhere around us – in books, journals, newspapers, prints of famous paintings, and also in everyday things like theatre programmes, official circulars, calendars, diaries, advertisements, cinema posters at street corners.

1. What does the geology of the peninsular plateau show?

The geology of the peninsular plateau shows that it constitutes one of the ancient landmasses on the earth’s surface. It was supposed to be one of the most stable blocks.

In 1900, a popular music publisher E.T. Paull produced a music book that had a picture on the cover page announcing the ‘Dawn of the Century’. At the centre of the picture is a goddess-like figure, the angel of progress, bearing the flag of the new century. She is gently perched on a wheel with wings, symbolising time.

In 1848, Frédéric Sorrieu, a French artist, prepared a series of four prints visualising his dream of a world made up of ‘democratic and social Republics’, as he called them. The first print of the series, shows the peoples of Europe and America - men and women of all ages and social classes - marching in a long train, and offering homage to the statue of Liberty as they pass by it.

The French Revolution opened up the possibility of creating a dramatic change in the way in which society was structured. Before the eighteenth century society was broadly divided into estates and orders and it was the aristocracy and church which controlled economic and social power.

A lot of this diversity is fast disappearing. Between 1700 and 1995, the period of industrialisation, 13.9 million sq km of forest or 9.3 per cent of the world’s total area was cleared for industrial uses, cultivation, pastures and fuelwood.

An event for an experiment is the collection of some outcomes of the experiment. The Probability of an event lies between 0 and 1 (0 and 1 inclusive).

An arithmetic progression is a list of numbers in which each term is obtained by adding a fixed number to the preceding term except the first term.

To locate the position of an object or a point in a plane, we require two perpendicular lines. One of them is horizontal, and the other is vertical. The plane is called the Cartesian, or coordinate plane and the lines are called the coordinate axes.

Facts or figures, collected with a definite purpose, are called data. Statistics is the area of study dealing with the presentation, analysis and interpretation of data. How data can be presented graphically in the form of bar graphs, histograms and frequency polygons.

A circle is the collection of all points in a plane, which are equidistant from a fixed point in the plane.

Area of a figure is a number (in some unit) associated with the part of the plane enclosed by that figure. Two congruent figures have equal areas but the converse need not be true.

Two figures are congruent, if they are of the same shape and of the same size. Two circles of the same radii are congruent. Two squares of the same sides are congruent.

The various components of an ecosystem are interdependent. The producers make the energy from sunlight available to the rest of the ecosystem. There is a loss of energy as we go from one trophic level to the next, this limits the number of trophic levels in a food-chain.

When we talk of ‘globalisation’ we often refer to an economic system that has emerged since the last 50 years or so. But as you will see in this chapter, the making of the global world has a long history - of trade, of migration, of people in search of work, the movement of capital, and much else.

As you have seen, modern nationalism in Europe came to be associated with the formation of nation-states. It also meant a change in people’s understanding of who they were, and what defined their identity and sense of belonging.

On the morning of 14 July 1789, the city of Paris was in a state of alarm. The king had commanded troops to move into the city. Rumours spread that he would soon order the army to open fire upon the citizens.

In this chapter you will read about nomadic pastoralists. Nomads are people who do not live in one place but move from one area to another to earn their living. In many parts of India we can see nomadic pastoralists on the move with their herds of goats and sheep, or camels and cattle.

In the spring of 1945, a little eleven-year-old German boy called Helmuth was lying in bed when he overheard his parents discussing something in serious tones.

One type of polynomial is the quadratic polynomial of the form ax² + bx + c, a ≠ 0. When you equate this polynomial to zero, you get a quadratic equation. Quadratic equations come up when you deal with many real-life situations.

Euclid’s division algorithm, as the name suggests, has to do with divisibility of integers. Stated simply, it says any positive integer a can be divided by another positive integer b in such a way that it leaves a remainder r that is smaller than b.

Trigonometry is one of the most ancient subjects studied by scholars all over the world. Trigonometry was invented because its need arose in astronomy. Since then the astronomers have used it, for instance, to calculate distances from the Earth to the planets and stars.

The word ‘trigonometry’ is derived from the Greek words ‘tri’ (meaning three), ‘gon’ (meaning sides) and ‘metron’ (meaning measure). trigonometry is the study of relationships between the sides and angles of a triangle.

A polynomial p(x) in one variable x is an algebraic expression in x of the form

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 linear equation in two variables has infinitely many solutions.

A number r is called a rational number, if it can be written in the form p/q, where p and q are integers and q ≠ 0. A number s is called a irrational number, if it cannot be written in the form p/q, where p and q are integers and q ≠ 0.

So far, you have been dealing with figures that can be easily drawn on our notebooks or blackboards. These are called plane figures.

Light seems to travel in straight lines. Mirrors and lenses form images of objects. Images can be either real or virtual, depending on the position of the object.

Carbon is a versatile element that forms the basis for all living organisms and many of the things we use. This large variety of compounds is formed by carbon because of its tetravalency and the property of catenation that it exhibits.

A compass needle is a small magnet. Its one end, which points towards north, is called a north pole, and the other end, which points towards south, is called a south pole. A magnetic field exists in the region surrounding a magnet, in which the force of the magnet can be detected.

Control and coordination are the functions of the nervous system and hormones in our bodies. The responses of the nervous system can be classified as reflex action, voluntary action or involuntary action.

Acid-base indicators are dyes or mixtures of dyes which are used to indicate the presence of acids and bases. Acidic nature of a substance is due to the formation of H⁺ (aq) ions in solution. Formation of OH^– (aq) ions in solution is responsible for the basic nature of a substance.

Motion is a change of position. It can be described in terms of the distance moved or the displacement. The motion of an object could be uniform or non-uniform depending on whether its velocity is constant or changing.

Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. The unit of work is joule: 1 joule = 1 newton × 1 metre.

The law of gravitation states that the force of attraction between any two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them. The law applies to objects anywhere in the universe. Such a law is said to be universal.

Sum of the

If a ray stands on a line, then the sum of the two adjacent angles so formed is 180° and vice-versa. This property is called as the Linear pair axiom. If two lines intersect each other, then the vertically opposite angles are equal.

Movement of various types can be taken as an indication of life. Maintenance of life requires processes like nutrition, respiration, transport of materials within the body and excretion of waste products.

A complete chemical equation represents the reactants, products and their physical states symbolically. A chemical equation is balanced so that the numbers of atoms of each type involved in a chemical reaction are the same on the reactant and product sides of the equation. Equations must always be balanced.

Variations arising during the process of reproduction can be inherited. These variations may lead to increased survival of the individuals. Sexually reproducing individuals have two copies of genes for the same trait. If the copies are not identical, the trait that gets expressed is called the dominant trait and the other is called the recessive trait.

Elements can be classified as metals and non-metals. Metals are lustrous, malleable, ductile and are good conductors of heat and electricity. They are solids at room temperature, except mercury which is a liquid. Metals can form positive ions by losing electrons to non-metals.

A stream of electrons moving through a conductor constitutes an electric current. Conventionally, the direction of current is taken opposite to the direction of flow of electrons. The SI unit of electric current is ampere.

Sound is produced due to vibration of different objects. Sound travels as a longitudinal wave through a material medium. Sound travels as successive compressions and rarefactions in the medium. In sound propagation, it is the energy of the sound that travels and not the particles of the medium. Sound cannot travel in vacuum.

The fundamental organisational unit of life is the cell. Cells are enclosed by a plasma membrane composed of lipids and proteins. The cell membrane is an active part of the cell. It regulates the movement of materials between the ordered interior of the cell and the outer environment.

Credit for the discovery of electron and proton goes to J.J.Thomson and E.Goldstein, respectively. J.J. Thomson proposed that electrons are embedded in a positive sphere. Rutherford’s alpha-particle scattering experiment led to the discovery of the atomic nucleus.

During a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is known as the Law of Conservation of Mass.

First law of motion: An object continues to be in a state of rest or of uniform motion along a straight line unless acted upon by an unbalanced force.