Combustion and Flame — Science STD 8 — Question

How can you reduce the drag on something moving through the air?

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?

Name the publication which contains record if all the endangered species (plants and animals, etc).

Water is not used to control fires Involving electrical equipment.

The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?

Which parts wear away first in shoes? Give a reason for your answer.

What is meant by 'reflected ray'?

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

What happens when:
Dilute sulphuric acid is poured on a copper plate?
Write word equations of the reactions involved.

Explain why, objects moving in fluids should have streamlined shape.