The operating system and application software are available in two fortns. They are:
i) Free and Open source
ii) Paid and Proprietary Software
i) Free and Open source
1. Free and open software is available at free of cost and can be shared to many end users.
2. Free software is editable and customizable by the user and this leads to updation or development of new software.
3. Examples of Free and Open source software are: LINUX, Open office, Geogebra etc.
ii) Paid and Proprietary Software
1. There are software that need a license to use it.
2. They have to be paid for using either permanently or temporarily,
3. The license of the software would not be provided unless itis purchased.
4. Similarly the end users are legally prohibited to steal the software program or to use the pirated version of the Paid and Proprietary Software.
5. Some of the examples of Paid and Proprietary Software are: Windows, Microsoft office, Adobe Photoshop, etc.

Physical changes
i) Breaking of a stick into two pieces
ii) Burning of a paper
iii) Tearing paper into small pieces
Chemical changes
i) Dissolving of sugar in water
ii) Burning of petrol or LPG gas
iii) Water boiling into water vapour
iv) Coconut oil becoming solid during winter

The main reasons for water scarcity
i) Population explosion
ii) Uneven distribution of rainfall
iii) Decline of ground water table
iv) Pollution of water
v) Careless use of water

i) Water is available in nature in three forms -, Solid, Liquid, Vapour. ~
ii) Solid form of water - Ice - It is present in icebergs and ice caps on top of tall mountains, galaciers and polar regions. 
iii) Liquid form, of water -  Water - It is present in oceans, seas, lakes, rivers and even underground.
iv) Gaseous form of water - Vapour -It is present in the air around us.

(i) Like human being, animals also depend on plants for their necessity.
(ii) Silk worm eat mulbery leaves and produce silk.
(iii) Animals, insects and birds help in cross pollination.
(iv) Entering of insects into the flower leads to pollination. It increases yield of crop.
(v) Plants and algae living in coral reefs are the food variety of fishes and fisheries work is done in these areas.
(vi) Animals and plants are play an important role in spreading of seeds.

(i) Timber is used to build houses and in making furniture.
(ii) We use wood for these purposes due to their features like durability, stylish finishing and resistance to temperature changes.
(iii) Commercial timber is classified into hardwood and softwood.
(iv) Hardwood is used in construction work and in making furniture.
(v) Softwoods have a wide range of applications such as making plywood and paper making.

(i) Noise pollution affects the environment. Unpleasant or loud sounds distrub us. This is called as noise pollution.
(ii) Loud music the sounds of motor vehicles, fireworks and machines causes noise pollution.
(iii) Continuous noise disturbs our sleep and does not let us to study and also it make stress and health impacts.
(iv) It is also disturb animals, bird and whales in under water.
(v) To reduce noise pollution lower the volume when you watch TV or listen to music.
(vi) Remind drivers not to use the horm too much.
(vii) Avoid fire works and do not speak loudly.

AVOID:
Avoid the usage of unwanted materials which create more debris.
(e.g) (i) Avoid buying packaged foods.
(ii) Refuse to buy use and throw plastic products.
REDUCE:
We can reduce the waste by using durable goods that last longer instead of things that are used once and thrown away.
(e.g) (i) Write both sides of papers.
(ii) Instead of unnecessary printing use electronic facilities.

Aim: Soap manufacturing.
Requirements:
i) 35 ml of water.
ii) 10 ml of NaOH.
iii) 60 ml of coconut oil.
Procedure:
i) Cover your work area with old newspaper.
ii) Take 35 ml of water in a jar.
iii) Add 10 gram of concentrated NaOH and allow it to cool.
iv) Then add 60 ml of coconut oil drop by drop and stir it well.
v) On getting dried, soap can be obtained.

(i) Dr. Rajendra Singh is known as "Waterman of India".
(ii) He is a well - known water conservationist and environmentalist.
(iii) His team built rainwater storage tanks, check dams and other timetested as well as path - breaking techniques.
(iv) His team built over 8600 johads to collect rain water for all seasons. It has brought water back to over 1000 villages and revived five rivers in Rajasthan.
Awards:
(i) He won stockholm water prize in 2005, an award known as "The Noble Prize for water".
(ii) Ramon Magsaysay Award in 2001.
(iii) Jamnalal Bajaj Award in 2005.

(i) Potable water is the water which is safe to drink. On an average the human body requires 2-3 liters of water per day for proper functioning.
(ii) It is transparent.
(iii) It is odourless and colourless.
(iv) Cleaned of harmful contaminants.
(v) It is harmless or free from disease causing bacteria.

i) Electromagnets are used in electromagnetic trains.
ii) Electromagnets are magnetised when current flows through them. When the direction of current is changed, poles will be changed.
iii) Magnets are attached at the bottom of the train and rail tracks.
iv) The train is lifted from track upto 10 cm height by the property of some poles that repel each other.
v) By using attraction and repulsion at the same time between the magnets in tracks and bottom of the train it moves forward.
vi) The magnets are controlled by electricity.
vii) There is no friction. So the train can easily attain a speed of 300 km/h.

i) Place the iron needle on a table. Now take a bar magnet and place one of its poles near one edge of iron needle and rub from one end to another end without changing the direction of the pole of the magnet. Repeat the process for 30 to 40 times.
ii) Bring a pin or some iron filings near the iron needle to check whether it has become a magnet. Does the iron needle attract the pin / Iron filing? If not continue the same process for some more time.

A huge envelope of air surrounded the earth is called Atmosphere.
(i) This envelope is thicker near the earth's surface.
(ii) As we go higher up, the density and the availabillty of air gradually decreases.
(iii) Movement of wind, Presence of water vapours for cloud formation are the vital roles of atmosphere.
(iv) Troposphere is the responsible layer for the weather we experience on earth.
(v) Stratosphere has the Ozone layer which protects all life on earth from the harmful UV rays of the sun.

(a) Slow and fast change
(i) Slowchange - Changeofseasons
(ii) Fast change - Bursting of fire crackers
(b) Reversible and irreversible change
(i) Reversible change - Stretching of rubber
(ii) Irreversible change - Digestion of food
(c) Physical and chemical change
(i) Physical change - Melting of Ice
(ii) Chemical change - Rusting of Iron
(d) Natural and man-made change
(i) Natural change - Rotation of the earth
(ii) Man-made change - Cooking
(e) Desirable and undesirable change
(i) Desirable change - Milk changing to curd
(ii) Undesirable change - Deforestation

Conductors:
(i) The rate of flow of electric charges in a circuit is called electric current.
(ii) The materials which allow electric charges to pass through them are called conductors.
(iii) Examples: Copper, iron, aluminium, impure water, eafth etc.
Insulators (Non -Conductors) : 
(i) The material which do not allow electric charges to pass through them are called insulators or non- conductors.
(ii) Examples: plastic, glass, wood, rubber, chinna clav, ebonite etc.

We get electricity from thermal power, hydel power, tidal power wind power, solar power etc as sources of electricity
Thermal Power stations:
In thermal power stations, the thermal energy generated by burning coal, diesel or gas is used to produce steam. The steam is used to rotate the turbine. While the turbine rotates, the coil of wire kept between the electromagnet rotates. Due to electro magnetic induction electricity is produced. Here heat energy is converted into electrical energy.
Hydel power stations:
In hydel power stations, the turbine is made to rotate by the flow of water from dams to produce electricity. Here kinetic energy is converted into electrical energy. Hydel stations have long economic lives and low operating cost.
Atomic power stations:
In atomic power stations, nuclear energy is used to boil water. Here the steam is used to rotate the turbine. As a result, electricity is produced. Atomic power stations are also called as nuclear power stations. Here nuclear energy is converted into mechanical energy and then electrical energy.
Wind Mills:
In wind mills, wind energy is used to rotate the turbine to produce electricity. Here kinetic energy is converted into electrical energy.

(i) Computers are used in various fields.
(ii) In textile shop it is used for billing.
(iii) Computers are used to control large and small machines.
(iv) Computers are most important educational tools for teachers and learners.
(v) In Railways it is useful to book tickets and for other purposes.
(vi) It is also used in banks, ATM's, Post offices and in many places.
(vii) We can save many data and convert it into information.

(1) The camel has long legs which help it to keep its body away from the hot sand in the desert.
(2) It can store large amount of water in its body.
(3) it loses very little water from its body through excretion.
(4) A camel's hump has fat stored in it. It ups the stored fat when required.
(5) It has large and flat padded feet to walk easily on soft sand.
(6) It has long eye lashes and hairs to protect its eyes and ears from the blowing dust.
(7) It can keep its nostrils closed to avoid dust.

FUNCTIONS OF THE ROOT:
i) The root fixes the plant to the soil.
ii) Absorbs water and minerals from the soil.
iii) Stores food in some plants like Carrot and beetroot
FUNCTIONS OF THE STEM:
i) The stem supports the branches, leaves, flowers and fruits.
ii) Transports Water and minerals from roots to upper aerial plant parts.
iii) Transports the prepared food from leaves to other parts through stem.
iv) Stores food as in the case of sugarcane

Linear motion - A coconut falling from a tree
Curvilinear motion - A car driving around a curve
Self rotatory motion - Motion of the wheel in a cart
Circular motion - Athlete running around a track
Oscillatory motion - Swinging of a pendulum
Irregular motion - Movement of people in a bazaar

When there is a change of position of an object with respect to time then it is called motion.
Types of motion:
a) Based on path:
i) Linear motion - a person walking on a straight path
ii) Curvilinear motion - throwing ball
iii) Circular motion - swirling stone tied to the rope
iv) Rotatory motion - a rotating top
v) Oscillatory motion - pendulum of clock
vi) Zig zag (or) Irregular motion - the motion of a bee
b) Based on duration:
i) period motion - movement of hour hand of a clock
ii) Non-periodic  - motion flapping of a flag in wind
c) Based on speed:
9) Uniform motion -  motion of a train at a constant speed
ii) Non-uniform motion - a vehicle moves in different speed

Method 1:
(i) Place a string along the curved line, Make sure that the stringcovers every bit of the curved line.
(ii) Mark the points where the curved line begins and ends on the string.
(iii) Now, stretch the string along the length of a meter scale and measure the distance between the two markings of the string.
(iv) This will give us the length of a curved line.
Method 2:
(i) Draw a curved line AB on a piece of paper.
(ii) Separate the legs of the divider by 0.5 cm or 1 cm using a ruler.
(iii) Place it on the curved line starting from one end. Mark the position of the other end. Move it along the line again and again cutting the line into number of segments of equal lengths. The remaining parts of the line can be measured using a scale.
(iv) Count the number of segments.
(v) Therefore, the length of the line = (number of segments x length of each segment) + length of the left over part.

While swallowing food if the food particles enter into respiratory tract leads to hiccup and cough to eject out the food particles from respiratory tract.

If the diaphragm is not moved, breathing will not occur. It leads to death.

Fire extinguishers throw a stream of carbon-, di-oxide while putting - off fire. Carbon-di-oxide covers the fire and cut-off the supply of fresh air to the burning things and stop burning.

a) melting of wax and
d) Solidification of the molten wax can be reversed.
Burning of candle is a physical / reversible change. That is,
\(\text { Solid wax } \underset{\text { Cooling }}{\stackrel{\text { Heating }}{\rightleftarrows}} \text { molten wax }\)

Many of us expect that diameter of hole will decrease, but actually as the diameter of ring increases diameter of hole will also increase.

We feel hot because the heat is transferred from atmosphere to your body. Heat energy flows from higher temperature to lower temperature.

(i) Using beakers, the mustard oil is separated by the process of decantation, because oil being lighter than water, floats on water.
(ii) Next filtration is using a funnel and filter paper and thus water gets separated from chalk powder and coins.
(iii) By hand-picking method, the coins are separated frorn chalk powder.

1.  Millimetre
2.  Second
3. Error
4. Time
5. Mass
6. Average
7. Length
8. Odometer
9. Tape
10. Litre