Micro-Organisms: Friends and Foe — Science STD 8 — Question

Describe how coal is formed from dead vegetation. What is this process called ?

The water which we get from sources such as taps, hand pumps, well and ponds is good conductor of electricity. Why?

Why plastic is lighter than metal?

Explain how elements and compounds differ in composition and properties.

Electroplating is a very useful process. Explain how.

A marble is allowed to roll down an inclined plane from a fixed height. At the foot of the inclined plane, it moves on a horizontal surface (a) covered with silk cloth, (b) covered with a layer of sand and (c) covered with a glass sheet. On which surface, will the marble move the shortest distance. Give reason for your answer.

Describe characteristics and uses of coke.

In an electroscope, if a negatively charged body is brought in contact with the metal clip, the strips of the electroscope diverge. If now another charged object carrying equal amount of positive charge is brought in contact with the clip, what will happen?

What is the similarity between electrostatic and magnetic forces?