Question

While lighting a candle, Paheli observed the following changes
(i) Wax was melting.
(ii) Candle was burning.
(iii) Size of the candle was reducing.
(iv) Melted wax was getting solidified.
Of the above, the changes that can be reversed are:
[2 marks]
[NCERT Exemplar Q.4]
[Reversible changes]

• A. (i) and (iv)
• B. (i) and (ii)
• C. (iii) and (iv)
• D. (ii) and (iii)

Answer 1

The correct option is A (i) and (iv)

Solution:

• Solid wax melts on heating and melted wax solidifies on cooling. Therefore, the melting of wax and its solidification are reversible changes. [1 mark]
• Burning of the candle is an irreversible change as wax once burnt cannot be obtained back. [0.5 marks]
• Reduction in the size of the candle is an irreversible change as the size of the candle once reduced upon burning cannot be increased. [0.5 marks]