Explain why the following are made of thermosetting plastics

Explanation:

• The given substances, i.e. Saucepan handles and Electric plugs/switches/plug boards are made of thermosetting materials, as these are poor heat and electrical conductors.
• They also don't usually bend or deform.
• After heating and shaping pressure, thermosetting polymers harden permanently.

Final answer:

Hence, (a) Saucepan handles and (b) Electric plugs/switches/plug boards are made of thermosetting plastics because they have poor conduction of electricity and are durable.