Class Notes NCERT Solutions for CBSE Students
Question: ‘Avoid plastics as far as possible’. Comment on this advice.
Answer: We know that plastic is non-biodegradable. This means that plastic waste is getting accumulated in our environment. Accumulation of plastic waste is creating a huge problem for us. Hence, we should avoid plastic as far as possible. We should switch over to biodegradable alternatives wherever possible. For example; we should use shopping bags made up of jute or cloth instead of plastic.
Question: ‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
Answer: Synthetic fibres have replaced natural fibres for most uses. It has resulted in reducing our dependency on natural fibres. Many natural fibres come from plants and hence plants need to be cut to obtain these fibres. Less demand for natural fibres means there is reduced need to cut trees. It has helped in conservation of forests. Hence, it can be said that manufacturing synthetic fibres is actually helping conservation of forests.
Question: Describe an activity to show that thermoplastic is a poor conductor of electricity.
Answer: For this, take a small piece of thermoplastic, some copper wires, two electric cells (from torch) and an electric bulb (from torch).
- Connect the bulb with the battery, and attach the thermosetting plastic to wires; to make a circuit.
- It is observed that the bulb does not glow.
- When thermosetting plastic is replaced with a metal rod in the circuit, the bulb begins to glow.
- This shows that thermosetting plastic is a poor conductor of electricity.
Question: Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.
Answer: Purpose of the handle of a toothbrush is different from the purpose of bristles of the toothbrush. The handle needs to be strong and less flexible. The bristles need to be highly flexible, soft yet durable. Hence, bristles need to be made up of different material than the material of toothbrush handle.
