This set of Extractive Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Unit Processes for Metal Extraction – Set 2”.
1. The reactions in which calcium can be used to reduce oxides are called ______
a) calthermic reduction
b) calciothermic reduction
c) calcium reduction
d) chalcothermic reduction
View Answer
Explanation: The reactions in which calcium can be used to reduce oxides are called calciothermic reduction reaction. Calcium is capable of reducing many oxides because it can form stable compound CaO.
2. Which element is produced using the Kroll’s process?
a) Uranium
b) Aluminium
c) Titanium
d) Tungsten
View Answer
Explanation: In Kroll’s process, magnesium is used to reduce halides. Titanium is produced using this process. The complete reaction of this process is: TiCl4 (l) + 2Mg (l) = 2MgCl2 (l) + Ti(s).
3. For practical uses, on which of the following factors a reduction reaction does not depend on?
a) Size of the container in which the reaction takes place
b) Reaction rate
c) Physical properties of reactants
d) Physical properties of products
View Answer
Explanation: Theoretically, we know that stable oxides are formed by metals after replacing the metals from less stable oxides but that’s not true practically every time. The reaction depends on factors like reaction rate, physical properties of reactants and products.
4. How can we make the formation of liquid slag a lot easier?
a) By adding a catalyst
b) By adding a fluxing agent
c) By increasing the temperature
d) By adding more amount of ore
View Answer
Explanation: Metals are easily removed if there is a liquid slag. The formation of a liquid slag can be made easier by adding a fluxing agent like lime to the ore. This slag with gangue forms a silicate multicomponent slag.
5. How to make the removal of the slag easier which is very much viscous?
a) By adding more amount of ore
b) By adding a fluxing agent
c) By increasing their viscosity
d) By decreasing their viscosity
View Answer
Explanation: To make the removal of a viscous slag easier, we have to decrease its viscosity. The viscosity of a slag depends on less mobile silicate ions. This can be done by adding a basic oxide or we can also increase its temperature.
6. We can classify slags which are used in smelting based on silicate degree.
a) True
b) False
View Answer
Explanation: The statement is true. We can classify the slags used in smelting based on silicate degree which are basic slags, neutral slags and acid slags.
7. What is the expression for calculating a silicate degree?
a) (Moles of acidic oxygen from oxides like CaO, MgO etc.) / (Moles of basic oxygen from SiO2)
b) (Moles of basic oxygen from oxides like CaO, MgO etc.) / (Moles of acidic oxygen from SiO2)
c) (Moles of basic oxygen from SiO2) / (Moles of acidic oxygen from oxides like CaO, MgO etc.)
d) (Moles of acidic oxygen from SiO2) / (Moles of basic oxygen from oxides like CaO, MgO etc.)
View Answer
Explanation: Silicates are minerals which essentially contain silicon and oxygen. We can find the silicate degree by taking the ratio of moles of oxygen in acidic oxide to the moles of oxygen in basic oxides.
8. What is the silicate degree of a basic slag?
a) Greater than 2
b) Greater than 1
c) Less than 1
d) Equal to 1
View Answer
Explanation: If we have the number of moles of oxygen in basic oxide more than the acidic oxide, then, definitely the silicate degree for basic slag will be less than 1. Similarly, we can predict the silicate degree for neutral and acid slag.
Sanfoundry Global Education & Learning Series – Extractive Metallurgy.
To practice all areas of Extractive Metallurgy, here is complete set of Multiple Choice Questions and Answers.
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