Sound — Science STD 8 — Question

Ankur's mother told him to wash his hands with soap before eating because his hands might have bacteria. Ankur did not believe her because he could not see anything on his hands. Why could not Ankur see the bacteria on his hands ? Why washing hands with soap and water before eating is generally recommended ? State how bacteria can be harmful to humans ?

We say fossil fuels will last only for a few hundred years. Comment.

Discuss the effects of deforestation :Environment

What is meant by inexhaustible natural resources? Name two inexhaustible natural resources.

Give one example of a solution.

Name the process by which plant material (or vegetation) buried deep under the earth was slowly converted into coal.

In which part of the sky can you find Venus if it is visible as an Evening Star?

Write in brief, how does a bicycle stop when its brakes are applied?

Which type of reflection of light, regular reflection or diffuse reflection, leads to the formation of images?

We have learnt that vibration is necessary for producing sound. Explain why the sound produced by every vibrating body cannot be heard by us?