Question

Which of the following change cannot be reversed?

• A. Hardening of cement
• B. Freezing of ice cream
• C. Opening a door
• D. Melting of chocolate

Answer 1

The correct option is A

Hardening of cement

Explanation for correct option:

(A) Hardening of cement

Irreversible changes

• Irreversible changes are permanent changes.
• Chemical changes are generally irreversible changes.
• Examples are Cooking food and the formation of water from Hydrogen as well as oxygen.
• The hardening of cement cannot be reversed as once hardened it cannot revert back into its original form.
• During the hardening process cement undergoes a chemical process and sets into hard mass permanently which can not be reversed.

Explanation for incorrect options:

Reversible changes

• Any changes which can be reversed or are a temporary conversion are known as Reversible changes.
• Physical changes are generally reversible.
• Examples of reversible changes are Melting, freezing, boiling water, etc

Thus, options B, C, and D are incorrect.

Hence, the correct option is A i.e. Hardening of cement.