Class 8 Science - Chapter Some Natural Phenomena NCERT Solutions | When a glass rod is rubbed with a piece

Describe with the help of a diagram an instrument which can be used to detect a charged body.

Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?

Sometime, a crackling sound is heard while taking off sweater during winters. Explain.

Explain why a charged body loses its charge if we touch it with our hand.

Suggest three measures to protect ourselves from lightning.

Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?

Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?

List three states in India where earthquakes are more likely to strike.

The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.

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.

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)

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.

What are the different ways in which water gets contaminated ?

Explain the importance of reproduction in organisms.

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.

Match the organisms in Column I with their action in Column II.
      Column I                           Column II
  (i) Bacteria                       (a) Fixing Nitrogen
  (ii) Rhizobium                  (b) Setting of curd
  (iii) Lactobacillus             (c) Baking of bread
  (iv) Yeast                         (d) Causing Malaria
  (v) A protozoan               (e) Causing Cholera
  (vi) A Virus                      (f) Causing AIDS
                                          (g) Producing antibodies

What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?

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

‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.

Give the full form of IVF.

How are babies produced through IVF technique? What are such babies called?

What are the advantages of using CNG and LPG as fuels?

Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?

Fill in the blanks with appropriate words:

(a) Synthetic fibres are also called ______ or _______ fibres.
(b) Synthetic fibres are synthesised from raw material called ________.
(c) Like synthetic fibres, plastic is also a __________ .