Is distilled water a mixture or a pure substance?

Hint: As we know that the molecular formula of water is \[{{\text{H}}_{\text{2}}}{\text{O}}\]. The molecular weight of water is \[{\text{18g}}\]. The water has intermolecular hydrogen bonding between the water molecules. The water can exist in all the states of matter. A solid state of water is called an ice cube. The gas state of water is called water vapour. The liquid state of water is called such water.

 Complete answer:
The purification of water is important in chemical sciences. Once purification of water by distillation is the best technique. After the distillation of water, it comes in pure substance.
According to the above discussion, we conclude distilled water is an example of a pure substance.

 Note:
We have to know that water is classified as two types. This classification is based on the amounts of minerals. The two types of water are hard water and soft water. The hard water means water contains high amounts of minerals ions. The soft water means water contains low amounts of minerals ions. The hardness of water is divided into two types. There are temporary and permanent hardness of water. This classification of hardness is dependent on the salt contained in the water. Sodium chloride is salt present in water. The boiling point of water is less than the boiling point of salt. The sodium chloride salt has an ionic bond between sodium ion and chlorine ion. But water molecules have only covalent bonds between hydrogen and oxygen atoms in the molecules and hydrogen bonds between other water molecules. Hence, the boiling point of salt is greater than water.