Question

An iron ring is heated. Which of the following statement about it is incorrect?

• A. The ring expands.
• B. The ring almost comes to the same size on cooling.
• C. The change, in this case, is reversed.
• D. The ring changes its shape and the change cannot be reversed.

Answer 1

The correct option is D

The ring changes its shape and the change cannot be reversed.

Explanation:

(D): Iron is a metal and it expands on heating. It regains its original shape and size when it cools down.

• The change is reversible in the case of an iron ring as the expansion of the ring only occurs when heat is supplied.

Reversible changes: Changes that can be reversed or are a temporary conversion are known as reversible changes.

• Processes such as melting, boiling, evaporation, freezing, condensation, and dissolution are reversible changes.
• Examples: Melting of wax, freezing of ice, boiling water which evaporates as steam and condenses back to the water, etc.

Irreversible changes: Irreversible changes are permanent changes.

• Reactants react to form an entirely new compound and cannot be reversed.
• Processes like burning, mixing, and powdering are a few processes that cause irreversible changes.
• Examples: Burning of a piece of paper, cooking of raw egg, etc.

Hence, option (D) is correct.