Why does a lump of cotton wool shrink in water?
Air is dissolved in water and this can be showed by an experiment.
Diagram:
This proves that air dissolves in water.
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?
What is the composition of air?
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.
How are cactus adapted to survive in a desert?
Explain why the bulb would not glow in the arrangement shown in Fig. 12.13.
Explain, why speed is important for survival in the grasslands for animals that live there. (Hint: There are few trees or places for animals to hide in grasslands habitats.)
Fill in the blanks :
(a) A device that is used to break an electric circuit is called _______________.
(b) An electric cell has _______________ terminals.
Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving
sugar? In which case would it be possible to dissolve more sugar?
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
Why do we need to separate different components of a mixture? Give two examples.
Select those objects from the following which shine:
Glass bowl, plastic toy, steel spoon, cotton shirt
How are clouds formed?
Which of the non-living things listed below, were once part of a living thing?
Butter, Leather, Soil, Wool, Electric bulb, Cooking oil, Salt, Apple, Rubber