Question

Which of the following is reversible change?
A) Cutting wood into pieces
B) Blooming of flowers
C) Melting of ice
D) The burning of candles

Answer 1

Hint: As we know that a thermodynamic process is said to be reversible if the process can be turned back such that both the system and the surroundings return to their original states, with no other change anywhere else in the universe. The reversible processes can easily be defined as idealizations or models of real processes, on which the limits of the system or device are to be defined.

Complete answer:
We will look at all the options one by one:
Option A) this option is incorrect as cutting wood into pieces is not a reversible change as wood cannot be reversed back into its original form once broken.
Option B) this option is incorrect.
Option C) this is a correct option as the melted ice cube may be refrozen, so melting is a reversible physical change. Physical changes that involve a change of state are all reversible. Other changes of state include vaporization (liquid to gas), freezing (liquid to solid), and condensation (gas to liquid). Dissolving is also a reversible physical change.
Option D) this option is incorrect as after burning the candle cannot be back to its original form thus it’s an irreversible process.

OPtion C is the correct answer.

Note:
We need to know that an irreversible process can be defined as a process in which the system and the surroundings do not return to their original condition once the process is initiated. The irreversible process is the natural process that is commonly found in nature. When we tear a page from our notebooks, we cannot change this and 'un-tear'. This is an irreversible process.