Iron is made inactive or passive by:

1. H₃PO₄

2. conc. HNO₃

3. conc. H₂SO₄

4. dil. HNO₃

The inner lining of a blast furnace is  made up of:

1. graphite bricks

2. silica  bricks

3. fire clay bricks

4. basic bricks

Froth floatation process for the concentration of ores is a practical application of:

1. adsorption

2. absorption

3. coagulation

4. sedimentation

Roasting is generally carried out in case of :

1. Oxide ores

2. Sulphide ores

3. Silicate ores

4. Carbonate ores

Which substance is used as basic refractory material in furnace?

1. Al₂O₃

2. SiO₂

3. CaO

4. Fe₂O₃

Rutile is an ore of:

1. Ti

2. Zr

3. Mn

4. V

Which is not a mineral?

1. Mica

2. Peat

3. Quartz

4. Felspar

Which element is purified by Zone refining?

1. Ge

2. Ge and Si

3. Si

4. None

Alloy is an example of:

1. gel

2. aerosol

3. solid sol

4. emulsion

The second most common element on the earth is:

1. silicon

2. hydrogen

3. nitrogen

4. oxygen