NEET Practice Questions (MCQs) with Answers & Solutions

GANGUE is rock or mineral matter of no value occurring with the metallic ore in a vein or deposit

Al₂O₃.2H₂O + 3C+N₂ $\to$2AlN+3CO + 2H₂O

In the metallurgy of copper, slag is FeSiO_3.

ZnS reacts with NaCN to form soluble complex. So, NaCN is used as depressant.

Ore  of Ag i.e. Argentite (Ag2S) form soluble complex with NaCN.

Ag₂S + 4NaCN $\rightleftharpoons$$\frac{\begin{array}{c}\begin{array}{c}\begin{array}{c}2Na\left[Ag\right(CN{)}_2]\\ Sodium Argento cyanide\end{array}\end{array}\end{array}}{(soluble complex)}$+ Na₂S

Vapour phase refining Vapour phase refining is the process of refining metal by converting it into its volatile compound and then, decomposing it to obtain a pure metal. 

Metal is converted into volatile compound and then decomposed to obtain pure metal. This method is used for refining $Ni,Zr$ and $Ti$.

$Ni$ is heated with $CO$ to form volatile nickel tetracarbonyl.
Ni+4CO - 330−350K-​ Ni(CO)4​

At high temperature, nickel tetracarbonyl decomposes to pure Ni.
Ni(CO)4​ - 450−470K​  Ni+4CO
This is Mond's process for refining Ni.

Van-Arkel method is used for ultrapure metals like Ti, Zr, Hf etc. The metal is converted into its volatile stable compound such as TiI4, leaving behind the impurities. The stable volatile compound thus formed is decomposed to get the pure metal.

German silver is (Ni + Cu + Zn)