Metallurgical Processes

Chemisorption is a sub-class of adsorption, driven by a chemical reaction occurring at the exposed surface. A new chemical species is generated at the adsorbant surface e.g., corrosion, metallic oxidation. The strong interaction between the adsorbate and the substrate surface creates new types of electronic bonds - ionic or covalent, depending on the reactive chemical species involved.

A number of metals such as silver, gold and platinum, have been obtained in colloidal state by treating the aqueous solution of their salts, with a suitable reducing agent such as formaldehyde, phenyl hydrazine, hydrogen peroxide, stannous chloride etc..

Laterite forms in tropical regions with high rainfall through intense leaching of silica and soluble minerals, leaving behind iron and aluminum oxides. The oxidation process gives laterite its characteristic red color. Hydration, carbonation, hydrolysis, and calcification contribute to soil formation but leaching+oxidation is most critical for laterite.

In electroplating, the object to be coated is made the cathode (negative electrode). Metal ions from the anode solution deposit onto the cathode surface.

The substances that are capable of withstanding very high temperatures without melting or becoming soft are called refractory materials like- SiC (carborundum), Al₂O₃, SiO_2, etc. Blast furnace is used or the smelting of iron, copper and lead ores. Calamine (ZnCO₃) is the ore of zinc while casseterite (SnO₂) is the ore of Sn.

The metallic luster (shine) is caused by free electrons in the metal that reflect light. When light strikes the metal surface, these delocalized electrons vibrate and re-emit the light, creating the characteristic shine. This property is related to electrical and thermal conductivity of metals.

Benzotriazole is a heterocyclic compound. It is commonly used as a corrosion inhibitor. It is a colourless solid that is soluble in polar solvents, including water. Benzotriazoles are also a class of compounds containing the benzotriazole skeleton.

 Rusting of iron takes place due to oxidation.

Iron reacts with atmospheric oxygen and moisture to form rust or iron oxide. The rusting of iron is called corrosion.

 This is the correct option. Painting, greasing, alloying, galvanisation and electroplating are all good methods of prevention of corrosion.

This is the correct option. Acids are never stored in metal containers because they gradually corrode and eat up the metal container.

this is the only way to change copper into gold would be to add 50 protons to the nucleus.

Germanium tetrachloride is a colourless liquid used as an intermediate in the production of purified germanium metal. In recent years the usage of GeCl₄ has increased substantially due to its use as a reagent for fibre optic production.

Tin cans are used for storing foods and are made by electroplating tin instead of iron because tin is less reactive than iron and does not react with food.