Thomas slag is:

1. calcium silicate

2. calcium  phosphate

3. tricalcium phosphate and calcium silicate

4. calcium ammonium phosphate

Corundum is:

1. SrO₂

2. Al₂O₃

3. CaCl₂

4. Cu₂Cl₂

Heating of carbonate ores to remove carbon is called as:

1. Roasting

2. Calcination

3. Smelting

4. Fluxing

Sulphide ores are common for the metals:

1. Ag, Cu and Pb

2. Ag, Cu and Sn

3. Ag, Mg and Pb

4. Al, Cu and Pb

Which element occurs freely in nature?

1. Iodine

2. Sulphur

3. Phosphorus

4. Magnesium

Silver obtained by argentiferrous lead is purified by:

1. distillation

2. froth floatation

3. cupellation

4. reacting with KCN

Which process is not used in purification of bauxite?

1. Hall's method

2. Baeyer's method

3. Serpek's method

4. Frankland's method

Chloride ore among the following is:

1. malachite

2. magnesite

3. magnetite

4. Karnalite

Chalcogens are: 

1. hydrocarbons 

2. ore forming elements 

3. oxide forming elements

4. those having ability to catenate

The following equation represents a method of purification of nickel by,

Ni + 2CO $\stackrel{320\mathrm{K}}{\to }$Ni(CO)₄ $\stackrel{420\mathrm{K}}{\to }$Ni +4CO this method is:

impure                                 pure

1. Cupellation

2. Mond's process

3. Van Arkel method

4. Zone refining