Stars and the solar system. — Science STD 8 — Question

A student staying in a coastal region tests the drinking water and also the sea water 'With a circuit in which a part of the connecting wire is wound around a matchbox containing compass. He finds that the compass needle deflects more in the case of sea water. Can you explain the reason?

What is the name of passage in outer ear which carries sound waves to the eardrum?

Name the scale on which the magnitude (or intensity) of an earthquake is expressed.

Describe the threat to Taj Mahal monument due to air pollution.

How can a very heavy machine be moved conveniently from one place to another in a factory? (No crane is available for this purpose).

Name three types of substances in which an electric current can produce a chemical effect.

Can you hold a hot metallic pan which is without a plastic or a wooden handle? Give reason for your answer.

Your parents are going to buy a house. They have been offered one house on the roadside and another house three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.

State two physical properties on the basis of which metals can be distinguished from non-metals.

State whether plastic is biodegradable or non-biodegradable? Give reasons for your answer.