Question

Give reason for the following - 1) sulphur is used in the vulcanisation of rubber. 2)iron is used for constructing bridges and houses. 3) copper is used for electrical wires. 4)aluminium foils are used to wrap food items. 5) graphite is used as an electrod in dry cells.

Answer 1

Dear Student

1. Vulcanization of natural rubber is done to improve its properties. In this process, a mixture of raw rubber with sulphur and appropriate additive is heated at a temperature range between 373 K and 415 K.

2. Iron is a metal with good tensile strength and hence it is used for the construction of bridges and houses.

3. 1. Copper is a good conductor and has a very low resistance.
2. It is ductile.
3. It is cheap.

4.

Aluminium is a good conductor of heat, on the other hand its is a bad radiator of heat, therefore when we wrap hot food in the aluminium foil it keep the food warm.

Aluminium on reaction with oxygen forms a layer of Al₂O₃ which renders the metal passive and protects it from further reaction. Hence it is not harmful for us.

Thus, aluminium doesn't react with our food therefore we can use it for wrapping purposes. However, we should not pack pickle in aluminium foil as it contains citric acids, which reacts with Al foil and hence can harm us.

5. Graphite is a good conductor of electricity. Therefore, graphite is used for making dry cell electrodes.

Regards