31.

One of the following metals forms a volatile compound and this property is taken advantage for its extraction. This metal is:

• iron

• nickel

• cobalt

• tungsten

Percentage of silver in the alloy German siiver is:

• 0%

• 1.0%

• 2.5%

• 1.5%

Which of the following is coinage metal?

• Cu

• Sn

• Zn

• Pb

Gold is extracted by hydrometallurgical process, based on its property :

• of being electropositive

• of being less reactive

• to form complexes which are water soluble

• to form salts which are water soluble

The temperature of the slag zone in metallurgy of iron using blast furnace is :

• 1200-1500°C

• 1500-1600°C

• 400-700°C

• 800-1000°C

Which ofthe following pairs of elements can not form an alloy ?

• Zn , Cu

• Fe , Hg

• Fe , C

• Hg , Na

Assertion : Hydrometallurgy involves dissolving the ore in a suitable reagent followed by precipitation by a more electropositive metal.

Reason : Copper is extracted by hydrometallurgy.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false

• If both assertion and reason are false.

Which of the following elements is present as the impurity to the maximum extent in pig iron ?

• Phosphorus

• Manganese

• Carbon

• Silicon

Which metallurgy does not involve leaching ?

• Fe

• Ag

• Au

• Al

The present undesirable matrix in mineral is called as :

• flux

• slag

• gangue

• alloy