Question

8. Which of the steps while burning a candle is not reversible?

• A. Melting of solid wax
• B. Wax vapour burn into flame
• C. Liquid wax changes into vapours
• D. All of the above

Answer 1

The correct option is B

Wax vapour burn into flame

Explanation for correct option:

(B) During burning, wax vapours changes into flame and produce some of the gases. These gases cannot be reversed back to the wax. Therefore, changing of wax vapours into flame is an irreversible change.

Explanation for incorrect options:

(A) Melting of solid wax is a reversible change as the melted wax can be reversed back to solid state on cooling.

(C) Changing of liquid wax into vapours is a reversible change as the vapours can be reversed back to liquid wax on codensation.

Hence, option (C) is correct.