Class 6 Science - Chapter Changes Around Us NCERT Solutions | Give examples to explain the difference

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?

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?

A drawing sheet changes when you draw a picture on it. Can you reverse this change?

To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?

You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?

Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.

(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.

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.

What is a habitat?

Fill up the blanks
(a) The presence of specific features, which enable a plant or an animal to live in a particular habitat, is called .
(b) The habitats of the plants and animals that live on land are called habitat.
(c) The habitats of plants and animals that live in water are called habitat.
(d) Soil, water and air are the ———— factors of a habitat.
(e) Changes in our surroundings that make us respond to them, are called .

Which of the things in the following list are nonliving?
Plough, Mushroom, Sewing machine, Radio, Boat, Water hyacinth, Earthworm

Give two examples each, of modes of transport used on land, water and air.

How is a compass used to find directions?

True or false?
(a) A mixture of milk and water can be separated by filtration.
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing.                                                                                                                (c) Separation of sugar from tea can be done with filtration.
(d) Grain and husk can be separated with the process of decantation.

How will you separate sand and water from their mixture?

How would you obtain clear water from a sample of muddy water?

How do plants and animals help each other in the exchange of gases in the atmosphere?

The handles of the tools like screwdrivers and pliers used by electricians for repair work usually have plastic or rubber covers on them. Can you explain why?

A magnet was brought from different directions towards a toy boat that has been floating in water in a tub. Affect observed in each case is stated in Column I. Possible reasons for the observed affects are mentioned in Column II. Match the statements given in Column I with those in Column II.

Column I                                                                        Column II

Boat gets attracted towards the magnet                          Boat is fitted with a magnet with north pole towards its head

Boat is not affected by the magnet                                   Boat is fitted with a magnet with south pole towards its head

Boat moves towards the magnet if north                          Boat has a small magnet fixed along its length
pole of the magnet is brought near its
head

Boat moves away from the magnet                                  Boat is made of magnetic material                                                                                                             when north pole is brought near its head 

Boat floats without changing its direction                         Boat is made up non-magnetic material