Question

Which of the following can be categorised as both chemical and physical change?

• A. Formation of curd from milk.
• B. Melting of wax in a candle.
• C. Both melting of wax and formation of curd from milk.
• D. Neither melting of wax and formation of curd from milk.

Answer 1

The correct option is D

Neither melting of wax and formation of curd from milk.

Formation of curd from milk is an irreversible change, as milk cannot be obtained back from curd.
Melting of wax in a candle is a reversible change, as wax can be solidified and can be converted back to a candle.
But in general, there is no reaction which is both reversible as well as irreversible.