Class 8 Science - Chapter Pollution of Air and Water NCERT Solutions | You are a member of the municipal body o

Describe the threat to the beauty of the Taj Mahal.

Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

Which of the following is not a greenhouse gas?
(a) Carbon dioxide
(b) Sulphur dioxide                                                                                                                                                                                                                                  (c) Methane
(d Nitrogen

Prepare a brief speech on global warming that you have to make in your class.

Explain circumstances leading to acid rain. How does acid rain affect us?

Clear, transparent water is always fit for drinking. Comment.

Describe the ‘Green House Effect’ in your own words.

What are the different ways in which water gets contaminated ?

Explain the differences between pure air and polluted air.

At an individual level, how can you help reduce air pollution?

Which of the following can be beaten into thin sheets?
  (a) Zinc     (b) Phosphorus     (c) Sulphur     (d) Oxygen

Fill in the blanks
(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.
(b) The passage of an electric current through a solution causes ______________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the terminal of the battery.
(d) The process of depositing a layer ofany desired metal on another material by means of electricity is called .

Give two examples each of situations in which you push or pull to change the state of motion of objects.

Fill in the blanks:
(a) Friction opposes the _____________ between the surfaces in contact with each other.
(b) Friction depends on the _____________ of surfaces.                                                                                                                                                                      (c) Friction produces __________.
(d) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction.

List conditions under which combustion can take place.

Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape. (T/F)

Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth.

Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called                  .
(b) Species found only in a particular area is known as                          .
(c) Migratory birds fly to far away places because of                     changes.

Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.

Explain the importance of reproduction in organisms.

What will happen if:
(a) we go on cutting trees.
(b) the habitat of an animal is disturbed.
(c) the top layer of soil is exposed.

Explain how deforestation leads to reduced rainfall.

Write short notes on the following:
(a) Cytoplasm
(b) Nucleus of a cell

Name three liquids, which when tested in the manner shown in Fig.14.9, may cause the magnetic needle to deflect.

Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

Explain why chloroplasts are found only in plant cells?

Word game : Use the clues to work out the words.

Across
3. Protruding voice box in boys
4. Glands without ducts
7. Endocrine gland attached to brain
8. Secretion of endocrine glands
9. Pancreatic hormone
10. Female hormone

Down
1. Male hormone
2. Secretes thyroxine
3. Another term for teenage
5. Hormone reaches here through blood stream
6. Voice box
7. Term for changes at adolescence

Match items in column A with one or more items in column B:

A                                           B
(i) Inner planets                 (a) Saturn
(ii) Outer planets               (b) Pole Star
(iii) Constellation               (c) Great Bear
(iv) Satellite of the Earth   (d) Moon
                                          (e) Earth
                                          (f) Orion
                                          (g) Mars

What is the term used for secretions of endocrine glands responsible for changes taking place in the body?

Give two examples of situations in which applied force causes a change in the shape of an object.