What is the composition of air?
Air contains 21% of oxygen, 78% nitrogen, 0.03% carbon dioxide other gases like argon, dust particles, water vapours present in 0.01% quantity. Oxygen gas is very necessary for the respiration of organisms. Oxygen helps in burning; nitrogen gas is present in the large amount but it cannot help in burning process.
How will you prove that air supports burning?
How do plants and animals help each other in the exchange of gases in the atmosphere?
List five activities that are possible due to the presence of air.
The layer of air around the earth is known as ___________.
How will you show that air is dissolved in water?
Why does a lump of cotton wool shrink in water?
The component of air used by green plants to make their food, is ___________.
Which gas in the atmosphere is essential for respiration?
(a) Which kind of garbage is not converted into compost by the redworms?
(b) Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Do you find that all living beings need the same kind of food?
Name the major nutrients in our food.
Classify the following fibres as natural or synthetic:
nylon, wool, cotton, silk, polyester, jute
Name five objects which can be made from wood.
Why do we need to separate different components of a mixture? Give two examples.
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal.
Fill in the blanks:
(a) Joints of the bones help in the ——————— of the body.
(b) A combination of bones and cartilages forms the _______ of the body.
(c) The bones at the elbow are joined by a ______________________ joint.
(d) The contraction of the _____________ pulls the bones during movement.
Give two examples each, of modes of transport used on land, water and air.
When does a drought occur?
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
Why can a pace or a footstep not be used as a standard unit of length?
(a)Collect different kinds of packaging material. What was the purpose for which each one was used? Discuss in groups.
(b) Give an example in which packaging could have been reduced?
(c) Write a story on how packaging increases the amount of garbage.
(a) Collect pieces of different kinds of paper. Find out which of these can be recycled.
(b) With the help of a lens look at the pieces of paper you collected for the above question. Do you see any difference in the material of recycled paper and a
new sheet of paper ?
A drawing sheet changes when you draw a picture on it. Can you reverse this change?
List all items known to you that float on water. Check and see if they will float on an oil or kerosene.
(a) Which kind of garbage is not converted into compost by the redworms?
(b) Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Give examples to explain the difference between changes that can or cannot be reversed.