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) 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.

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.

(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.

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

Jute crop is grown in seven states - West Bengal, Assam, Odisha, Bihar, Uttar Pradesh, Tripura and Meghalaya. West Bengal alone accounts for over '50% of raw jute production.

Consumers have different sources of food in an ecosystem and do not rely on only one species for their food. If we put all the food chains within an ecosystem together, then we end up with many interconnected food chains. This is called a food web.

Water is one of the basic substances present in the earth It plays a vital role in the evolution and survival of life. It is impossible to imagine life on the earth without water. Water helps to regulate the temperature of our planet. It also helps to maintain the temperature in organisms.

i) Unlike poles (S-N, N-S) attract each other.
ii) Like Poles (N-N, S-S) repel each other.

i) Natural ecosystem
ii) Artificial ecosystem are the two types of ecosystem.

(i) Cement becomes hardened when it is mixed with water.
(ii) It is necessary to control the rate of hardening.
(iii) so that, Gypsum is added to cement at the final grinding process.

Switch, Bulb and Battery are the parts of the electric circuit. Generator is the source of electricity.

Eyes, Ears, Nose, Tongue and Skin are the sense organs.

Plant cell,Animal cell and most of fungi.

If we remove the fish from the aquarium and keep it in a dark place with green plants,
(i) they can't have sunlight and
(ii) have no CO₂ from the water produced by fish as they breathe.
(iii) Simply say, there is no possibility for photosynthesis to make their food.

Plants decaying is a chemical change.

(i) The Water heater
(ii) Iron box
(iii) Electric kettle etc.

Printers and Monitors are output devices.

The locomotory organ of Amoeba is pseudopodia.

We have to separate mixture,
(i) to remoe impurities
(ii) to separate useful components
(iii) to get a highty pure form substance

Based on habitat, plant are classified as
i) aquatic plants
ii) terrestrial plants.

(i) Data is the information that has to be processed.
(ii) They are in the form of numbers, alphabets and images.

i) Common cold
ii) Influenza

c. Flash card

1 millimetre < 1 centimetre < 1 Metre < 1 kilometre.