Q: Calamine, malachite, magnetite and cryolite, respectively, are

aligned & Calamine ZnCO _3 \\ & Malachite CuCO _3 Cu ( OH )_2 \\ & Magnetite Fe _3 O _4 \\ & Cryolite Na _3 AlF _6 aligned

Question 1

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

Accepted Answer

During the extraction of copper, iron is present in the ore as impurity (FeS). The ore together with a little coke and silica is smelted; FeS present as impurity in the ore is oxidized to iron oxide, which then reacts with silica to form fusible ferrous silicate which is removed as slag. 2 FeS +3 O _2 2 FeO +2 SO _2

Question 2

Calamine, malachite, magnetite and cryolite, respectively, are

Accepted Answer

aligned & Calamine ZnCO _3 \ & Malachite CuCO _3 Cu ( OH )_2 \ & Magnetite Fe _3 O _4 \ & Cryolite Na _3 AlF _6 aligned

Question 3

The starting material for the manufacture of KMnO _4 is

Accepted Answer

Pyrolusite (It is MnO _2 )

Question 4

Identify the incorrect statement.

Accepted Answer

Gangue is the commercially worthless material which contaminates the ore.

Question 5

The reaction that does NOT take place in a blast furnace between 900 ~K to 1500 ~K temperature range during extraction of iron is :

Accepted Answer

At 900-1500 ~K (higher temperature range in the blast furnace) Reaction which take place are: C + CO _2 2 CO FeO + CO Fe + CO _2 CaO + SiO _2 CaSiO _3 (Slag formation) Fe _2 O _3+ CO 2 FeO + CO _2 at 500-800 ~K

Question 6

_ f G ^ - vs T plot in the Ellingham diagram slopes downward for the reaction

Accepted Answer

C ( s )+ 1 2 O _ 2 ( ~g ) CO ( g ) ; S increases. Hence, as the temperature increases, T S increases and hence G ( H - T S ) decreases. In other words, the slope of the curve for formation of CO decreases. However, for all other oxides, it increases.

General Principles and Processes of Isolation of Metals — Previous Year Questions & Solutions