Question

Which of the following changes is NOT a chemical change?
A. Boiling of water
B. Boiling of egg
C. Burning of paper
D. Burning of cloth

Answer 1

Hint: This question gives the knowledge about physical and chemical changes. Physical changes lead to changes in the appearance of the substances and chemical changes leads to changes in the entire compound and involves chemical reactions.

Complete answer:
Boiling of water is not a chemical change it is a physical change.
Physical changes lead to changes in the appearance of the substances. Physical changes undergo changes in physical properties such as size, shape and so forth. Generally, it undergoes a temporary change. During physical changes, new substances are not formed. Physical changes are reversible in nature which means parent compounds can be recovered at any point. Production of energy is not involved during physical changes.
Examples of physical changes are melting of wax, freezing of water, boiling of water, melting of ice, dissolving, bending, cutting, breaking of glass, cutting of wood, shredding of paper, mixing of sand with water, crushing a can, sublimation of dry ice and so forth.
Chemical changes do not lead to changes in the appearance of the substances. Chemical change is also called a chemical reaction. Generally, it undergoes a permanent change. During chemical changes, new substances are formed. Chemical changes are irreversible in nature which means parent compounds can never be recovered at any point. Production of energy is involved during physical changes. Both emission and absorption of energy occurs during chemical changes.
Examples of chemical changes are changing colors, precipitation, emission of gases, emission of odor, formation of new compounds during chemical reactions, change in oxidation state and so forth.
Therefore, option, ‘A. Boiling of water’ is correct.

Note: Always remember the difference between chemical change and physical change. Physical changes are temporary changes whereas chemical changes are permanent changes. During physical changes, new substances are not formed.