Is Matter Around Us Pure — Science STD 9 — Question

What is the reason for the identical chemical properties of all the isotopes of an element? Explain with the help of an example.

Give the names and symbols of five familiar substances which you think are elements.

‘A substance has a definite volume but no definite shape’. State whether this substance is a solid, a liquid or a gas.

What name is given to the amount of substance containing this number of atoms?

Name one non-metal which is liquid.

If the valency of carbon is 4 and that of sulphur is 2, work out the formula of the compound formed by the combination of carbon with sulphur. What is the name of this compound?

Name the discoveror of electrons, protons and neutrons.

Under which category of mixtures will you classify alloys and why?

If the valency of hydrogen is 1 and that of nitrogen is 3, work out the formula for ammonia.

State one use of radioactive isotopes in industry.