Test: Isolation of Elements - 1 (Old NCERT) - JEE MCQ

Silica is most common impurity present in ores.

Manganese is found in sea beds.

FeS₂ is iron pyrites.

FeCO₃ is siderite.

Process of removal of impurities from ore is known as concentration of ore or benefication of ore.

Levigation is process of grinding an insoluble substance to a fine powder while wet. The material is introduced into mill together with water. It is based on the density difference between ore and impurity.

Gavity separation is done maily for oxide ores.

This is hydraulic washing or gravity separation. Here whwn stream of water is passed it takes away all the impurity with it.

CN^- forms complex with gold or silver.

Liquification is purification technique used for metals having low melting points.

Fact

Al is generally used in paints and lacquers.

Hall – Heroult process of extraction of Al from Bauxite.

Nitrides are not found in Earth crust.

In froth floatation ore particles get wetted with oil and comes to the surface with froath.

Aniline stabalises the froath.

Bauxite ore have silica, Fe₂O₃, TiO₂ as impurity.

At this Temp range free energy for the process is negative.

Hence A is correct.

Ni is first reacted with CO to form Nickel tetracarbonyl which is volatile. From this complex Nickel is extracted by thermal decomposition.

Blistter Cu is 98% Cu.

Cupellation is a process where ores are treated under high temperatures and controlled operations to separate noble metals like gold and silver, from base metals like led, copper, zinc, and others present in the ore or alloyed metal.

Dolomite is MgCO₃.CaCO₃

Cyanide forms soluble complex with the gold.

Reduction of CO₂ to CO involves heat absorption.

Calamine is ore of zinc.