Question

Which of the following is true?
A. Melting of ice is reversible changes
B. Burning of magnesium is reversible changes
C. Rusting of iron is reversible changes
D. All of the above

Answer 1

Hint: A reversible chemical reaction is a reaction which could go in both directions, which is forward and backward, in other words reactants can turn into products, and products can turn back into reactants. This keeps repeating until the state of an equilibrium is reached, where both the process happens at the same rate and the amount of reactant and products stays the same.

Complete step by step answer:
We know that the melted ice cube may be refrozen, so we can say that the melting is a reversible physical change. Physical changes that involve a change of state are termed as reversible. Other changes of state may include vaporization (liquid to gas), freezing (liquid to solid), and condensation, (gas to liquid). Dissolving of a substance can also be characterised as a reversible physical change.
We know that there are two types of chemical changes that occur in nature that are exothermic and endothermic reactions. Magnesium ribbon is an elemental form after burning in the presence of oxygen in air, as it changes to oxide of magnesium also called magnesium oxide which is present in a powder form as there is a formation of a chemical, there is a breakdown of a chemical bond. So it is considered as a chemical change and not a reversible change.
Now if we look at the third option, we know that the rust is a type of crumbly, brown material which is caused due to the chemical reaction of iron, water and oxygen. It is an irreversible process as the damaged material or metal cannot be returned to its former or original state.

So, the correct answer is Option A.

Note: Burning of anything is an irreversible change as the material which is being burned cannot be turned back to its original state.
The reversible changes are those in which the material could be turned back to its original state, so the melting of an ice cube is a reversible change.