Chromium is obtained by reducing concentrated chromite ore with :

(a) red hot coke

(b) gaseous hydrogen 

(c) aluminium powder

(d) carbon monoxide  

The substance that acts as a collector in the froth flotation method is:

1. Sodium xenate.           

2. Sodium pyrophosphate.

3. Sodium nitroprusside.

4. Sodium ethyl xanthate. 

In the purification of impure nickel by Mond's process, metal is purified by:

(1) Electrolytic reduction

(2) Vapour phase thermal decomposition

(3) Thermite reduction

(4) Carbon reduction

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

The chemical composition of "slag" formed during the smelting process in the extraction of copper is :

(1) $C{u}_2+FeS$                                   

(2) FeSiO₃

(3) CuFeS                                         

(4) $C{u}_{2}S+FeO$

The basic principle of froth floatation is-

Out of the following which metal can be purified by Van Arkel method?

1.  Au

2.  Zr

3.  Ag

4.  Cu

During electrolysis of fused NaCl in order to obtain Na, ${\mathrm{H}}_2$ is liberated at the cathode of Pt while with the cathode of Hg, it forms sodium amalgam. This is because

(I)  Pt is inert

(2)  Hg is a liquid

(3)  More voltage is required to produce ${\mathrm{H}}_2$ at Hg than at Pt

(4)  ${\mathrm{H}}^{\oplus }$ ions are formed rapidly when Hg is used as a cathode

Which of the following is an incorrect match?

1. Kaolinite - Al₂(OH)₄Si₂O₅

2. Cuprite - Cu₂O

3. Siderite - FeCO₃

4. Calamine - ZnSO₄

Among the following a non-oxide ore is:

1. Malachite

2. Cuprite

3. Zincite

4. Bauxite