On heating blue colour copper sulphate loses its water molecules and becomes white.

Many salts are found as crystals with water molecules they contain. These water molecules are known as water of crystallisation.

Toothpastes which are generally basic and used for cleaning the teeth can neutralise the excess acid and prevent tooth decay.

Basic salts are the product formed by the partial replacement of hydroxide ions of a diacidic or triacidic base with an acid radical.
Pb(OH)₂+HCl⟶Pb(OH)Cl+H₂O

Double salts are the salts formed by the combination of the saturated solution of two simple salts in equimolar ratio followed by crystallization. For example: Potash alum.

Potash alum is a mixture of potassium sulphate and aluminium sulphate
KAll(SO₄)₂·12H₂O

It means the number of replaceable hydroxyl groups present in one molecule of a base

It is a mixture of hydrochloric acid and nitric acid prepared optimally in a molar ratio of 3: 1. It is a yellow-orange fuming liquid. It is a highly corrosive liquid, able to attack gold and other resistant substances.
i. Aquaregia is used to dissolve the noble metals such as gold, platinum and palladium.
ii. It is used for cleaning and refining gold.

Acids get ionised in water (produce H+ ions) completely or partially. Based on the extent of ionisation acids are classified as follows:
Strong Acids:
These are acids that ionise completely in water. Example: HCl
Weak Acids:
These are acids that ionise partially in water. Example: CH₃COOH

Acids present in plants and animals (living things) are organic acids.
Example: HCOOH, CH₃COOH