Question

Which of these are physical changes in matter? Check all that apply boiling water a pencil being sharpened exploding dynamite freezing water rotting cheese

Answer 1

Answer: Boiling water, pencil being sharpened, freezing water.

Explanation: Physical change is the change in which there is no rearrangement of atoms and there is change in size or shape of the substance.

Chemical change is the change in which there is rearrangement of atoms and the new substances get formed.

Boiling water only changes the phase from liquid to gas and thus is a physical change.

Pencil on being sharpened only gets smaller in size and thus is a physical change.

exploding dynamite would result into formation of new substances and hence a chemical change.

Freezing water only changes the phase from liquid to solid and thus is a physical change.

Rotting cheese would result in formation of new substances and hence a chemical change.

Answer 2

Explanation:

A change that does not lead to any difference in chemical composition of a substance is known as a physical change.

For example, shape, size, mass, volume, density, boiling point, etc of a substance are all physical properties.

On the other hand, changes that lead to bring change in chemical composition of a substance is known as a chemical change.

For example, exploding dynamite, rotting cheese etc are all chemical changes.

Thus, we can conclude that following are the physical changes in matter.

• boiling water.

• a pencil being sharpened.

• freezing water.