Matter in Our Surroundings — Science STD 9 — Question

What is the maximum number of electrons which can be accommodated in the:
Innermost shell of an atom?

What conclusion is obtained from the fact that all the gases form cathode rays?

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

What is the general name of:
Rigid form of matter?

Give a brief description of the following: 
Atomic mass unit.

Name the scientist who discovered the nucleus of atom.

Write the molecular formulae for the following compounds.
Calcium (II) phosphate.

Which of the following are not compounds?
Chlorine gas, Potassium chloride, Iron powder, Iron sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond.

A piece of chalk can be broken into small particles by hammering but a piece of iron cannot be broken into small particles by hammering. Which characteristic of the particles of matter is illustrated by these observations?

Give a brief description of the following:
Atomicity.