Science Write The Short Note.

1. A homogeneous mixture of two or more metals or of metals and non-metals is called an alloy.
2. They contain metals in specific proportions.
3. The physical properties of an alloy are different from those of its constituents, but chemical properties remain the same.
4. Copper and tin are used to make an alloy called bronze. It is hard and corrosion resistant.
5. When iron and carbon are mixed, an alloy steel is formed. It is a stronger material.
6. The alloy, stainless steel is made from iron, carbon, nickel and chromium. It is more durable, clean and does not rust.

By applying a layer of paint, oil, grease or varnish on the surface of a metal to prevent corrosion. Also plating with noncorroding metal is done. Iron is coated with thin layer of zinc. Due to these processes, the contact of a metal surface with air is lost and corrosion is prevented.

1. A reddish coloured deposit (rust) is formed on iron by reaction with oxygen gas.
2. A greenish coloured deposit (copper carbonate) is formed on copper by reaction with carbon dioxide.
3. A blackish coloured deposit is formed (silver sulphide) on silver.
4. Corrosion causes damages to car bodies, bridges, iron railings, ships specially those of iron, silver articles and copper vessels.

Uses of Nobel Metals:

1. Gold, silver and platinum are used to prepare ornaments.
2. Silver is used in medicines. (It has antibacterial property).
3. Gold and silver are also used to make metals and few electronic devices.
4. Platinum, palladium metals are used as catalyst. .