Metallurgical Processes

Corrosion is a gradual destruction of material usually metals by chemical reaction with its environment. This means the electrochemical oxidation of metals by reacting with an oxidant such as oxygen.

Aluminium foil is made from a big block of refined (pretty pure) aluminium. Aluminium foil is aluminium prepared in thin metal leaves with a thickness less than 0.2 millimetres.

Gold is a dense, soft, shiny, malleable and ductile metal. Gold readily creates alloys with many other metals. The extreme malleability, ductility and softness of pure gold make it practically useless for jewellery applications. The addition of alloying elements (other metals) to gold is used to increase the toughness and hardness of the metal. 

Galvanization is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting. Although galvanization can be done with electrochemical and electrodeposition processes, the most common method in current use is hot dip galvanization, in which steel parts are submerged in a bath of molten zinc.

It is because lead is less denser than mercury. Mercury is very heavy weighing 13.6 times to that of volume of water. Stone, iron, and even lead can float on its surface.

Invar also known as FeNi36 is a nickel iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or ل). The name comes from the word invariable referring to its lack of expansion or contraction with temperature changes.

A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass).

Galvanization is the specific process of coating iron or steel with zinc to prevent rusting. The zinc acts as a sacrificial metal, corroding in place of the iron. Electroplating is a broader term that can coat any metal onto another surface.

The plastic spoon will float and the steel spoon will sink. The plastic spoon is lighter than water.

The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.

Metallic objects are electroplated to protect the metal underneath and to make it attractive.

Chromium does not corrode and is scratch resistant. Chromium is neither cheap nor is it easily available. Electroplating of chromium is a complex and controlled process as the chromium layer tends to peel off.

Leblanc process is an industrial process for the production of soda ash (sodium carbonate, Na₂CO₃).

1. The floatation process is the concentration method of sulphide ores. Zinc ores, mainly ZnS, are concentrated by floatation method, then roasted in air to give ZnO and SO₃.
   1. Zn is used extensively for coating for the appliances made up of corrosive metals like Fe to prevent them from rusting.
   2. Cd metal absorbs neutrons very well and is used to make control rods in nuclear reactors.
   3. The largest use of mercury is in electrolytic cells for the production of sodium hydroxide and chlorine gas at commercial level. Hence, statements 2 and 3 are incorrect.

This option is correct because the mixture of iron ore, coke and limestone is called ‘charge’. Iron ore is not pure iron oxide; it also contains an assortment of rocky material. This wouldn't melt at the temperature of the furnace and would eventually clog it up. The limestone is added to convert this into slag which melts and runs to the bottom. The heat of the furnace decomposes the limestone to give calcium oxide.