Question

Choose the incorrect statement for chemical changes:-

• A. Exchange of energy takes place
• B. Change is temporary and irreversible
• C. New substances are formed
• D. Change in mass of the original substance

Answer 1

The correct option is B

Change is temporary and irreversible

Chemical changes are permanent changes and they may be reversible or irreversible both i.e. in some cases chemical changes are irreversible and in some cases they are reversible.

Example of chemical changes (irreversible):- Rusting of iron, Burning of fuel etc.

Examples of chemical changes (reversible):- When hydrated copper sulphate (blue colour) is heated it will form anhydrous copper sulphate (white) but this anyhydrous copper sulphate can again be reversed to give hydrated copper sulphate by addition of water.