If the aluminium salt of an anion X is Al₂X₃, what is the valency of X? What will be the formula of the magnesium salt of X?

Explain the formation of (i) sodium ion, and (ii) chloride ion, form their respective atoms giving the number of protons and number of electrons in each one of them. What is the reason for positive charge on a sodium ion and a negative charge on a chloride ion?

State the various postulates of Dalton’s atomic theory of matter.

Give the formulate of the compounds formed from the following sets of elements:

(a) calcium and fluorine

(b) hydrogen and sulphur

(c) nitrogen and hydrogen

(d) carbon and chlorine

(e) sodium and oxygen

(f) carbon and oxygen

Give a brief description of the following:

(i) Relative atomic mass

(ii) Atomic mass unit

(iii) Ions

(iv) Ionic compound

(v) Atomicity