Retro (Past 13 Year) JEE Main - Metallurgy - Class 12 MCQ

This problem involves the concept of Ellingham diagramas this diagram predicts the basis of oxidation state and stability of iron compounds.

The above given reaction series is incorrect. The correct reactions series is as follows :


This reaction series is also incorrect. The correct reaction series is 


The reaction of FeCI₃ is not possible. Thus, the above reaction series is incorrect.

This reaction series is correct.

van-Arkel method is used for refining titanium and zirconium. This method is use ful for removing volatile impurities Iike O₂, N₂, I₂ present in the metals of Zr and Ti.
In this method, metal iodide is formed by direct combination of metal and iodine.
The metal iodide undergo decomposition on a tungsten filament and thus, pure metal is deposited on the filament.

The value of ΔG for the formation of CO₂ is negative , i.e. it is thermodynamically more stable than CS₂. Also, metal sulphides are thermodynamically more stable than CS₂.
Metal sulphides are more stable than the corresponding oxides, so they are roasted to convert into less stable oxides.

During electrolysis,  noble metals (inert metals) like Ag , Au and Pt are not affected and separate as anode mud from the impure anode.

Froth floatation is used to concentrate sulphide ores (Galena (PbS)].

Aluminium is extracted by electrolysis of a fused mixture of alumina (2-8%), synthetic cryolite Na₃ AIF₆ (80-85%), AIF₃ and fluorspar. This makes alumina good conductor and lowers the fusion temperature also.

Cyanide process or Mac Arthur-Forest cyanide process 
2Ag₂S + 8NaCN + O₂ + 2H₂O → 4Na[Ag(CN)₂] + 4NaOH + 2S
Soluble silver complex is filtered and treated with zinc dust and silver gets precipitated.

For purification, impurities like Se, Te, Ag, Au gets oxidised (deelectronation) falling into solution near anode and settle as anode mud.