Synthetic Fibres and Plastics — Science STD 8 — Question

Explain how, deforestation makes the soil infertile leading to desertification.

In which of the following cases are all the examples correctly matched? Give reasons in support of your answers.
(i) Elements – water, nitrogen, iron, air.
(ii) Uniform mixtures – minerals, seawater, bronze, air.
(iii) Pure substances – carbon dioxide, iron, oxygen, sugar.
(iv) Non-uniform mixtures – air, sand, brass, muddy water.

We should use mobile phones rather than landline phones during thunderstorm. Give reasons.

An electric current is passed through a conducting solution. List any three possible observations.

State one advantage of maintaining Red Data Book.

What is a tissue? Give two examples of tissues.

Write the force with which the earth attracts the objects towards it.

Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify.

Why should we avoid standing close to a tuberculosis patient while he/ she is coughing?