Types of the solution: (1) Acidic with $$pH$$ less than 7. For example, aqueous solutions of $$HCl$$, $$H_2SO_4$$, acetic acid etc. (2) Neutral with $$pH$$ 7. For example pure water, aqueous $$NaCl$$ solution. (3) Basic with pH more than 7. For example, aqueous solutions of $$NaOH$$, $$KOH$$, $$NaHCO_3$$ etc.