Question

While melting a candle, paheli observed the following changes.(i) wax was melting,(ii)candle was burning ,(iii) size of the candle was reducing,(iv) melting wax was getting solidified.Of the above, the changes that can be reversed are

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

Answer 1

The correct option is D

i and iv

The explanation for the correct option

Option D I and iv

• Melting of wax and melting wax was getting solidified are reversible in nature as they can bring to their original form.
• Solid wax can be melted and melted wax can be solidified again and again.

The explanation for the incorrect options

Option A, i and ii

• Melting of wax is reversible but burning a candle is irreversible.
• In burning, the oxygen within in air reacts with the candle to produce carbon dioxide.
• A substance, CO2, is produced. The change is irreversible in nature.

Option B, i and iii

• The melting of wax is reversible in nature while the size of the candle was reduced in nature is irreversible.
• Once the size decreases cannot bring back to its original size.

Option C, iii and iv

• Once the size of the burning candle decreases, cannot bring back to its original size.
• In burning, the oxygen within in air reacts with the candle to produce carbon dioxide.
• Thus burning of a candle is irreversible in nature.

Thus Option D i and iv a correct option