Question

Define reversible, irreversible, physical and chemical changes.

Answer 1

Physical change or process does not alter the composition of a substance. Examples:

• Melting an ice cube.
• Boiling water.
• Breaking a glass.

Chemical changes occur when a substance combines with another to form a new substance. Examples:

• Souring milk.
• Digesting food.
• Cooking an egg

Reversible Changes are temporary and Irreversible changes are permanent changes. Examples:

• Reversible change: freezing water to make ice or melting chocolate.
• Irreversible change: burning of paper, Burning of fuels, Cooking of food, Rusting of iron