you already know that blowing air biowing air is called wind. wind is very useful for us wind power is uned for pumping water for irrigation generating electricty moving blades of windmills etc . but when the wind blowe too hard it causes a lot of destruction . strong winds may uproot trees destroy electricity and telephine lines ;

                                         Soil

soil is one of the most important natural resources. it is a mixture of different types of rock particles and remans of dead plants and animals soil is found all around us in gardens school playgound at the parks at construction sites around us in gardens school playground at the parks at construction sites and also in the fields. it lies beneath our feet and is often hidden by roads and buildings. prodably this is the reason we often fail to realize how much soil affects our lives.

                                                     uses of soil 

soil plays an important role in the survival of organisms on the earth. its uses are as  follows.

  soil is also very important as a habitat-a home for millions of soil organisms like insects. earthworms  bacteria fungi ect .

it provides anchorage to trees and vegetation. 

look around what do you see.

Many things a row of houses large trees small plants peopls birds animals and many othres.

Each house in your locality and alos elsewhere remains at its allotted plact the tree in near yous house remains there itself. birds keep flying from one place to another . they may sit for a while on a tree top people may sit or move from one place to another so we see there are two different types of odjects these are.

     .      the odjects which do not change thir position with time.

     .      the odjects which do not change their position with time are said to be at rest.

the objects which change their positions with time.

We use different kinds of substances in our homes every day . These substances include milk vinegar lime juice curd pure water baking soda salt sugar stain cleaner oven cleaner etc. All of these substance can be classified into acidic basic and neutral substances on the basis of their properties. 

                                     Acids

The word acid is derived from the latin word acidus meaning sour to taste. Acids are present in a number of food items life curd lemons raw mangoes tomatoes grapes apples tamarinds and vinegar.  Substances the contain acids are called acidic substances.

                                Reach for the Top 

 the onls woman in the word who has scaled mt everest twice was born in a society where the birth of a son was ragarded as a blessing and a daughter thuogh not considered a curse was not generally welcome .

When her mother was expecting santosh a travelling holy man giving her his blessing assumed that she wanted a son but to everyone surprise the unborn child grandmother who was standing close by told him that they did not want .

A son the holy man was also surprised nevertheleless he gave the requested blessing and as destiny would have it the blessing seemed to work santosh was born the sixth child in a family with five sons a sister to fivr broyhers. 

she was born in small village of joniyawas of rewari district in haryana.

the girl was given the name santosh which means contentment. but santosh was not always content with her place in a teaditonal way of life. she began living life on her own termays content with has place in a traditional way of start.

                     Fear no More

fear no more the heat the heat the sun not the furious winter rages thou thy worldly task hast dons thou thy wordiy task hast done home art gone and ta

en thy wages golden lads and girls all must golden lads and girls all must as chimney sweepers come to dust.

fear no more the frown the great thou art past the tyrant stroke care no more to clothe and eat To thee the reed is as the oak to the screptre learning physic must all follow this and come to dust fear no more the lightning flashy nor the all dreaded thunder stone fear not slander censure rash thuo hast

hast finished joy and moan all lovers young all lovers must consign to thee and come to dust.

A small cottage interior . there is an entrance back right [ which may be curtaineg ]. another door to the left must be a practical door.

the furniture is simpls consisting of a small tabie towards the left a chair or two and a divan rather upstage on the right. On the tabls is a tetephone. 

[ when the curtani rises gerrard is standing by the tabls making a phone call. he is of medium height and wearing horn rimmed glasses ......He is dressed in a lounge suit and a great coat. his voice is cultured.]

well tell him to phone up directly. i must know..... yes I expect i ii still be here but you mustn count on that in about ten minutes time. Right ho  goodbye.

any thing you like i know all the answers. but before we degin i should like to change my position you may be comfortable but i am not .

sit dowe there asd no funny business [ motions to a chair and seats himself on the divan by the bag ], now then we have a nice little talk about yourelf

  at last a sympathetic audience lll tell you the story of my life how as a child i was stolen by the gypsies and why at the age of thirty two i find myself in my lonely essex cottage how.....

You have learnt about physical and chemical changes in the previous class. You know  that a change in which  no new substances are formed and which can generate be reversed by reversing the conditiond  is called a physical change. In physical changes only the properties likes shape size colous or state of the substance get changed. The common examples of.  physical  changes are melting of ice melting of wax boiling of water dissolution of sugar in water etc.

The changes in which two or more substances react to form new substance having different properties are called chemical changes or reactions. Chemical changes take place  around us all the time.  Burning fuel cooking food. Photosynthesis  etc. Are the examples of chemical changes or reactions . In this chapter we will study more about chemical changes.

                                  SUBSTANCE

Any material with a specific chemical composition is called substances.  There are two major types of substances pure substance and mixture. 

Heat and temperature 

                 WHAT IS HEAT?

Sir Benjamin Thompson and James Prescott joule performed various experiments and explained  that heat is a from  of energy. We often describe different substances as hot or cold.  Hot and cold are relative terms. It means that something is considered as hot 

When it is compared to something which is colder.

Heat is a form of energy that spontaneously moves from the systems to its surroundings or vice versa. It happens due to the movement of tiny particles that  make up solids liquids and games.  If we put warm and cool objects together Heat is transferred from warm object to the cool object until both objects have the same temperature.  This stage is known as equilibrium stage. Hotness or coldness of a body is measured in as temperature.  The hotter an object is the higher is the temperature. Temperature is mostly measured degree Celsius ( *c ) 37.

Animals fibres

You have studied in previous classes that plant fibres mainly cotton and flax are major natural cellulose fibres. Cotton grows within a pod or bll from developing seeds and flax is obtained from  the start and riit of the plant. Let us now study about  silk and wool. These fibres are derived from the animals  so these are called animal fibres. 

Wool is the hair and fur of sheep and silk is the secretion of the silk caterpillar.  Protein fibres are hygroscopic they absorb moisture without feeling wet. In the winter when people go from dry indoor air into damp outdoor air wool absorbs moisture and generates heat protecting the Wearer from the cold.

                             Wool

We wear sweater in winter to protect ourselves from the cold. Wool is ideal for making such clothes. 

Wool can be obtained from hairy animals like sheep goat yek and camel. Llama and alpaca found in south America also yield wool. However sheep is the main source. The feence is cut off from the body of certain hairy animals to obtain wool. The process is called shearing.