An amalgam is an alloy which contains mercury as one of the component in it. Sodium-mercury amalgam, silver-mercury amalgam, etc. are examples.

Compare the following property of brass and copper: Corrosion resistance.

Brass is an alloy of copper and zinc. That is, the process of alloying make a substance corrosion resistant to a large extent whereas copper is a pure metal which can undergo corrosion due to porolonged exposure in air eventhough it is corrosion resistant. Therefore, we can say that brass is more corrosion resistant than copper.

Compare the following property of brass and copper: Hardness and strength

An alloy is more hard and has a greater strength than a pure metal. That is, brass is an alloy of copper and zinc whereas copper is a pure metal. Therefore, the hardness and strength is more in brass.

Compare the following property of brass and copper: Conductivity

An alloy has less conductivity than a pure metal. Brass is an alloy of copper and zinc and copper is a pure metal. Therefore, copper has more conductivity than brass.

Name the process by which impure ore of aluminium gets purified by using concentrated solution of an alkali.

Bayer's process is the process used for the purification of the impure ore of aluminium using concentrated solution of an alkali. In this process, finely powdered ore is treated with hot solution of sodium hydroxide.

Name the most common ore of the metal aluminium from which the metal is extracted. Write the chemical formula of the ore.

The most common ore of aluminium is the bauxite. It is an oxide ore. Bayer's process is used to obtain pure aluminium oxide from the bauxite ore. The chemical formula is A l 2 O 3 . The metal is extracted from this ore using the process called Hall-Heroult's process which involves the process of electrolysis.