CBSE NCERT Solutions for Class 8 Science Chapter 4

It is important for the students to keep these NCERT solutions while studying and refer to these to whenever a tough question comes in. The solutions cover each chapter and exercise from the class 8 science book.

CBSE NCERT Solutions for Class 8 Science Chapter 4:

Question-1:

Which of the following statements is correct?
a. All metals are ductile.
b. All non-metals are ductile.
c. Generally, metals are ductile.
d. Some non-metals are ductile.

Solution:

(c) Generally, metals are ductile. However, mercury metal - a liquid at room temperature - cannot be drawn into wires and is not ductile.

Question-2:

What happens when?
a. Dilute sulphuric acid is poured on a copper plate?
b. Iron nails are placed in copper sulphate Solution?
c. Write word equations of the reactions involved.

Solution:

a) When dilute sulphuric acid is poured on a copper plate, there will be evolution of hydrogen gas along with the formation of blue color crystals of copper sulphate.
CuSO4 + H2SO4 → CuSO4 + H2
b) Iron being more reactive displaces copper from copper sulphate Solution. In this reaction, the blue colour of copper sulphate fades and there is deposition of copper on the iron nails.
Fe + CuSO4 → FeSO4 + Cu

Question-3:

One day Rita went to a jeweller’s shop with her mother. Her mother gave an old gold
jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Solution:

To polish a gold ornament, it is dipped in a liquid called aqua regia (a mixture of
hydrochloric acid and nitric acid). On getting the environment of aqua regia, the outer layer of gold dissolves and the inner shiny layer appears. The dissolving of the layer causes a reduction in the weight of the jewellery.

Question-4:

Which of the following can be beaten into thin sheets?

  1. Zinc
  2. Phosphorus
  3. Sulphur
  4. Oxygen

Solution:

Zinc can be beaten into thin sheets.