Aluminium metal is purified by:
(1) Hoope's process
(2) Hall's process
(3) Serpeck's process
(4) Baeyer's process
AgCl on fusion with sodium carbonate, gives:
1.
2.
3.
4.
Select correct statement :
(a) The decomposition of an oxide into oxygen and metal vapour entropy increases
(b) Decomposition of an oxide is an endothermic change
(c) To make negative, temperature should be high enough so that T
(d) All are correct statements
When ZnS and PbS minerals are present together, then NaCN is added to separate them in the froth floation process as a depressant, because:
(a) is precipitated while no effect on ZnS
(b) ZnS forms soluble complex
(c) PbS forms soluble complex
(d) They cannot be separated by adding NaCN
Leaching of Ag2S is carried out by heating it with a dilute solution of:
1. NaCN only
2. HCl
3. NaOH
4. NaCN in presence of O2
Leaching is commercially carried out for in the concentration of:
(1) Galena
(2) Argentite
(3) Copper pyrites
(4) tin stone
A substance that can act as collector in the froth floatation method is -
1. Sodium xenate.
2. Sodium pyrophosphate.
3. Sodium nitroprusside.
4. Sodium ethyl xanthate.
(chromite) is converted to Cr by following steps :
Reagents in I, II and III step might be:
I-Step II-Step III-Step
(a) C C
(b)NaOH/air, C, Al,
(c) C, C,
(d)conc.
Incorrect statement for the Hall-Heroult process is:
1. | Cryolite Na3AlF6 lower the melting point of Al2O3, and increase its electrical conductivity. |
2. | Al is obtained at the cathode, and CO2 at the anode. |
3. | Li2CO3 can be used in place of cryolite(Na3AIF6) |
4. | MgF2 can be used in place of fluorspar (CaF2) |
Correct match is:
(1) Bayer's method
(2) Matte
(3) van Arkel method
(4) Thomas slag Raw material for cement industry
The reduction of an oxide by aluminium is called:
(1) Bayer's process
(2) Goldschmidt's aluminothermite process
(3) Hall's process
(4) van Arkel process
NaCN is sometimes added in the froth floatation process as a depressant when mineral contains ZnS and PbS because,
(A) is precipitated while there is no effect of ZnS.
(B) ZnS forms soluble complex while PbS forms froth.
(C) PbS forms soluble complex while ZnS forms froth.
(D) silicious impurities settle down on the bottom.
Main source of lead is galena (PbS). It is converted to Pb by:
(A)
(B)
(A) A (B) B
(C) both (D) none
The chemical composition of "slag" formed during the smelting process in the extraction of copper is:
1. Cu2 + FeS
2. FeSiO3
3. CuFeS
4. Cu2S + FeO
Pb and Sn are extracted from their chief ore by:
1. carbon reduction and self-reduction respectively.
2. self-reduction and carbon reduction respectively.
3. electrolysis and self-reduction respectively.
4. self-reduction and self-reduction respectively.
Which of the following statements is correct?
(1) In Hall-heroult process, the electrolyte used is a molten mixture of alumina, sodium hydroxide and cryolite.
(2) Lead is extracted from its chief ore by both carbon reduction and self reduction.
(3) Tin is extracted from its chief ore by carbon monoxide reduction.
(4) Siderite, cassiterite and argentite are carbonate ores.