Q12 of 26 Page 1

(i) Name the method of refining to obtain silicon of high purity.

(ii) What is the role of SiO2 in the extraction of copper?


(iii) What is the role of depressants in froth floatation process?


(i) Zone refining is the method of refining to obtain silicon of high purity. This method is used generally to obtain semiconductors of high purity like silicon.

(ii) During metallurgy, a flux is added which combines with the gangue and forms slag, which is easily separated from the ore to remove the gangue. SiO2 combines with the iron in the copper ore to form iron (II) silicate slag which is easily removed. Thus it (SiO2) acts as a flux to remove the impurity of Iron oxide.



(iii) In froth flotation process, depressant prevents the formation of froth. It is used to separate two sulphide ores by preventing the formation of froth of one sulphide ore and allowing the other to form the froth. For example, in an ore containing ZnS and PbS, NaCN, a depressant selectively prevents ZnS from coming in froth but allows PbS to come with the froth.


More from this chapter

All 26 →
10

Calculate the time to deposit 1.27 g of copper at cathode when a current of 2A was passed through the solution of CuSO4.

(Molar mass of Cu = 63.5 g mol-1, 1F = 96500 C mol-1).


 11

A solution is prepared by dissolved 10 g of non-volatile solute in 200 g of water. It has a vapour pressure of 31.84 mm Hg at 308 K. Calculate the molar mass of the solute.

(Vapour pressure of pure water at 308 K = 32 mm Hg).


 13

(i) Which one of the following is a polysaccharide :

Starch, maltose, fructose, glucose.


(ii) Write one difference between α-helix and β-pleated sheet structures of protein.


(iii) Write the name of the disease caused by the deficiency of vitamin B12


 14

(i) What type of isomerism is shown by the complex [Cr(H2O)6]Cl3?

(ii) On the basis of crystal field theory, write the electronic configuration for d4 ion if Δo > P.


(iii) Write the hybridization and shape of [CoF6]3.


(Atomic number of Co = 27).