Metallurgical Processes

This is the correct answer. Some quantities of manganese, are also required to harden the steel.

This option is correct because nickel formate is used as a catalyst in the hydrogenation of oils to form ghee.

Oxide film from steel pot is removed by the use of an acid such as hydrochloric acid.

Electrolytic refining is the standard industrial process used to obtain high-purity copper. Impure copper is used as the anode and pure copper as the cathode in an electrolyte solution.

This is the correct option as magnetisation of an iron bar is not done with the help of a chemical reaction.

This is the correct option as this statement is false. The process by which plants prepare their food is an example of a chemical change.

This is the correct option. Carbon and chromium are added into molten iron in fixed amounts to make an alloy called stainless steel.

This is the correct option. Crystallisation is the process of obtaining crystals from a hot saturated solution. Galvanisation is the process of coating thin layer of zinc on iron sheets. Rusting is the process due to which iron rusts in the moist air.

This is the correct option as the change that took place was not reversible. It is irreversible.

Laterite is produced by leaching and oxidation. Laterites are formed from the leaching of parent sedimentary rocks, metamorphic rocks and igneous rocks and mineralized proto-ores which leaves the more insoluble ions, predominantly iron and aluminium. 

 In the industrial production of vegetable ghee, the process involved is reduction.

Yes, this is correct , as corrosion of newly cut aluminium forms a layer of aluminium oxide which protects the aluminium from further corrosion.

The process of producing pure alumina from bauxite is known as Bayer's process - extraction, precipitation and calcination. The aluminium-bearing minerals in bauxite are selectively extracted from the insoluble components (mostly oxides) by dissolving them in a solution of sodium hydroxide (caustic soda).

The Dutch process (or stack process) was formerly the principal method by which white lead was prepared. It consisted building a stack of earthenware pots containing acetic acid upon a thick layer of spent  tanor manure and placing strips or coils of metallic lead over the pots; boards were then laid to form a false floor over the whole and more stacks built on top. The structure was then sealed and over time the metallic lead converted into lead carbonate corrosion caused by the action of the acetic acid vapour in the presence of carbon dioxide.

The production of aluminium by Hall's process was one of the earliest applications of electrolysis on a large scale, and is still the major method for obtaining that very useful metal. The process was discovered in 1886 by Charles M. Hall. Aluminium  is very reactive and therefore difficult to reduce from its compounds by chemical means. On the other hand, electrolysis of a molten aluminium salt or oxide is difficult because the salts are hard to obtain in anhydrous (dry) form and the oxide, Al₂O₃, does not melt until 3,762°F (2,072°C). Hall discovered that Al₂O₃, in the form of the mineral bauxite, dissolves in another aluminium mineral called cryolite, Na₃AlF₆, and that the resulting mixture could be melted fairly easily. When an electric current is passed through this molten mixture, the aluminium ions migrate to the cathode, where they are reduced to metal. At the anode, oxide ions are oxidised to oxygen gas.