Question

Which of the following is a correct example of physical change?

burning a piece of wood
oxidation of an object's surface
slicing through a block of sodium
changing the chemical identity of matter

Answer 1

The correct answer is C. Slicing through a block of sodium

Step-by-step explanation:

Physical changes imply a change in density, state, shape, volume, etc. of a substance, but not changes in the chemical properties or chemical composition of it. Due to this, physical changes include processes such as boiling a substance, cutting it or freezing it as these processes only affect physical properties. On the opposite, processes such as oxidation or combustion that affect the composition of a substance lead to chemical changes.

According to this, the one that is an example of physical change is "Slicing through a block of sodium" because this process involves only a change in the volume or shape of the substance that is the block of sodium which means it changes physically but its identity and chemical properties remain intact.

Answer 2

Answer: Option (c) is the correct answer.

Step-by-step explanation:

A physical change is defined as a change that does not cause any change in chemical composition of a substance.

For example, density, volume, malleability and ductility etc are all physical properties.

Whereas a chemical change is a change that causes change in chemical composition of a substance.

For example, reactivity, oxidation state, combustion, burning of wood etc are all chemical properties.

Therefore, we can conclude that out of the given options slicing through a block of sodium is a correct example of physical change.