Structure of the Atom — Science STD 9 — Question

Name a non-metal which is a good conductor of electricity.

Name one pair of substances whose mixture can be separated by fractional distillation.

What is meant by saying that non-metals are brittle?

Calculate the number of molecules in 8g of O₂.

When a crystal of potassium permanganate is placed in a beaker, its purple colour spreads throughout the water. What does this observation tell us about the nature of potassium permanganate and water?

Write the chemical formula using criss-cross method:
Ammonium sulphate.

Which single term is used to describe the mixing of copper sulphate and water kept in a beaker, on its own?

What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur?

Write the electronic configuration of the element with atomic number 17. Indicate the valency of the element.

What is the relationship between an atom containing 11 protons, 11 electrons ad 11 neutrons, and another atom containing 11 protons, 11 electrons and 12 neurtrons?