Class 8 Science - Chapter Pollution of Air and Water NCERT Solutions | Prepare a brief speech on global warming

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

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.

Explain the differences between pure air and polluted air.

What are the different ways in which water gets contaminated ?

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

You are a member of the municipal body of your town.

Make a list of measures that would help your town to ensure the supply of clean water to all its residents.

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.

Describe the construction of a kaleidoscope.

Explain the importance of reproduction in organisms.

What is menstruation? Explain.

Name the microorganisms which can fix atmospheric nitrogen in the soil.

A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

Make sketches of animal and plant cells. State three differences between them.

Tick the correct answer:

(a) Yeast is used in the production of
      (i) sugar     (ii) alcohol     (iii) hydrochloric acid     (iv) oxygen

(b) The following is an antibiotic
      (i) Sodium bicarbonate     (ii) Streptomycin      (iii) Alcohol     (iv) Yeast

(c) Carrier of malaria-causing protozoan is
      (i) female Anopheles mosquito     (ii) cockroach     (iii) housefly     (iv) butterfly

(d) The most common carrier of communicable diseases is
      (i) ant     (ii) housefly     (iii) dragonfly     (iv) spider

(e) The bread or idli dough rises because of
      (i) heat     (ii) grinding     (iii) growth of yeast cells     (iv) kneading

(f) The process of conversion of sugar into alcohol is called
     (i) nitrogen fixation     (ii) moulding     (iii) fermentation     (iv) infection

Make a sketch of the human nerve cell. What function do nerve cells perform?

Which part of the cell contains organelles?

Match items in column A with those in column B.
               A                                       B
  (i) Kharif crops                    (a) Food for cattle
  (ii) Rabi crops                     (b) Urea and super phosphate
  (iii) Chemical fertilisers       (c) Animal excreta, cow dung urine and plant waste
  (iv) Organic manure           (d) Wheat, gram, pea
                                             (e) Paddy and maize