5. What are noble metals? Why are they used to make ornaments?
6. Can a wire be drawn out of wood. Why not?
7. Can alloying be used to lower the melting point? Give an example.
8. How is anodizing of aluminium carried out?
Answers
Answer:
5)Noble metals are used to make ornaments because they having high resistance to corrosion even in adverse condition. The metals (e.g. gold, silver, or platinum) which resists chemical action, does not corrode, and is not easily attacked by acids are called noble metals.
6)No, a wire cannot be drawn out of wood. As wood is a non-metal, it does not hold the property of ductility. Ductility is the property of metals by which they can be drawn into wires.
7) Yes, alloying can be used to lower the melting point. Solder, an alloy of tin and lead, has a low melting point than that of tin and lead. Thus, this property of solder is helpful for copper wires to be used as a fuse in an electrical circuit
8)Anodizing is widely used for protecting aluminum via an oxidic protection-layer against corrosion. ... Then the anodizing process is performed in an electrolyte bath, commonly containing sulfuric acid. For this, the products are connected with the anode and hence an oxide layer is built on the surfaces of the parts.