Question

Knitting of wool into a sweater is a ___.

Answer 1

Step 1 Understanding the concept:

• Physical changes are reversible and do not produce a new substance.
• For example, Melting of ice and freezing of water are physical changes as there is no change in chemical composition, in both forms the chemical formula of water${\mathrm{H}}_2\mathrm{O}$ does not change.
• Chemical changes result in the production of a new substance and cannot be reversed.
• For example, the burning of paper(Carbon) results in the formation of carbon dioxide ${\mathrm{CO}}_2$ which is chemically different from paper made of carbon.

Step 2 conclusion:

• Knitting of wool into a sweater doesn't change the property of wool chemically.
• Thus Knitting of wool into a sweater is a physical change.