The group of atoms which carry a fixed charge (either positive or negative) on them and behave as ions are called polyatomic ions.
Example
(i) Carbonate ion
(ii) Sulphate ion
(iii) Ammonium ion
(iv) Phosphate ion
(i) The kind of person the doctor is (money, possessions)
(ii) The kind of person he wants to be (appearance, ambition)
∆ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB (see Fig. 7.34). Show that ∠ BCD is a right angle.
