Extraction of Aluminium

Q.

Answer the following question based on the extraction of aluminium from alumina by Hall-Heroults process:

1. What is the function of cryolite used along with alumina as the electrolyte?
2. Why is powdered coke sprinkled on the top of the electrolyte?
3. Name the electrode, from which aluminium is collected.

Q. Which of the following ores is concentrated by froth flotation process?

Q. Metal oxides of Ti, Cr and Fe can be reduced by Al in the Aluminothermic process.

1. True
2. False

Q.

Which of the following apparatus is used for carrying out the electrolysis of Lead bromide?

1. Glass vessel

2. Clay crucible

3. Silica crucible

4. Aluminium vessel

Q.

Complete the following

$2A{l}_2{O}_3+3C\to 4A+3B$. A & B are as follows.

1. Al, CO

2. CO, Al

3. Al, $C{O}_2$

4. $C{O}_2,Al$

Q. In the context of Hall-Heroult process for the extraction of Aluminium, which of the following statement is false?

1. $COandC{O}_2$ are produced in this process
2. $A{l}_2{O}_3$ is mixed with $Ca{F}_2$ which lowers the melting point of the mixture and enhances the conductivity
3. $A{l}^{3+}$ is reduced at the cathode to form $Al$
4. $N{a}_{3}Al{F}_6$ serves as the electrolyte

Q. Calcination does not work for:

1. Calamine
2. Malachite
3. Chalcopyrite
4. Dolomite

Q.

Which of the following are ores of copper?

1. Azurite

2. Malachite

3. Dolomite

4. Cuprite

Q.

During the high temperature non-aqueous electrolytic extraction of Aluminum from purified $A{l}_2{O}_3$, the oxygen evolved at the anode reacts with the electrode (graphite). As a result the electrodes are periodically replaced. – True or False?

1. True

2. False

Q. The process that yields 99.99% pure aluminium is:

1. Serpeck's process

2. Hall-Heroult process

3. Hoope's process

4. Bayer's process

Q. In Hall-Heroult process, $O_2$ evolved in anode reacts with graphite electrode results in the periodical replacement of electrodes

1. True
2. False

Q. $NaCN$ is sometimes added in the froth flotation process as a depressant when $ZnS$ and $PbS$ are to be separated in the given sample because:

1. $Pb(CN{)}_2$ is precipitated, no effect on $ZnS$
2. $ZnS$ forms a soluble complex, $PbS$ goes up with the froth
3. $NaCN$ reacts with $ZnS$ to form $N{a}_2\left[Zn\right(CN{)}_4]$
4. $Zn(CN{)}_2$ is precipitated, no effect on $PbS$