Take two wires. One wire is kept naked and another wire has plastic covering. Make two circuits, one with naked wire and another with plastic covering. We will feel shock with naked wire while plastic covered wire will not give any shock.

It shows that thermoplastic is a poor conductor of electricity.

We should avoid plastics as far as possible because plastics are non-biodegradable materials. Plastics take several years to decompose, thus cause environmental pollution. Burning of plastics releases poisonous gases into the atmosphere causing air pollution.

No, handle and bristles of a toothbrush should not be made of the same material because the handle should be hard while bristles should be made of the soft materials. Bristles should be soft so that it does not harm the gum of teeth. Handle should be made of hard material so that it gives the firm grip.

For making PVC pipes, thermoplastic is used.

Acrylic can be used as a substitute for wool for making sweaters and shawls.

Nylon is the first fully synthetic fibre.

(a) Nikita was aware that plastic is a non-biodegradable material. Disposal of plastic is a major problem. It is not easily decomposed by natural process. So, to avoid the use of plastic she prefer to take steel lunch box.
(b) No, plastic materials are not environment friendly since, it takes several years to decompose and causes environmental pollution. Besides, in the burning process it releases lots of poisonous fumes (gases) into the atmosphere causing air pollution.
(c) Nikita is very aware, sensible and intelligent girl.