Question

$\mathrm{Pb}$ and $\mathrm{Sn}$ are extracted from their chief ore by?

• A. self reduction and electrolysis respectively
• B. electrolysis and self reduction respectively
• C. carbon reduction and self reduction respectively
• D. self reduction and carbon reduction respectively

Answer 1

The correct option is D

self reduction and carbon reduction respectively

The correct option is (D):

Explanation for the correct answer:

Self reduction:

1. Self reduction basically means the species which will undergo the reduction itself and so acts as a reducing agent.
2. Basically, in this process the cations of the less electropositive metals such as the $\mathrm{Pb},\mathrm{Hg},\mathrm{Sb}\mathrm{and}\mathrm{Cu}$ will get reduced.
3. And this reduction can be done without the addition of any reducing agent.
4. Basically the elevated temperature as well as the anions that are associated with the metal will bring this change.
5. Therefore, Self reduction reaction of $\mathrm{Pb}$ is: $$\begin{gathered} \underset{\mathrm{Lead}\mathrm{Sulfide}}{2\mathrm{PbS}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Lead}\mathrm{oxide}}{2\mathrm{PbO}\left(\mathrm{s}\right)}+\underset{\mathrm{Sulfur}\mathrm{dioxide}}{2{\mathrm{SO}}_2\left(\mathrm{g}\right)} \\ \underset{\mathrm{Lead}\mathrm{sulfide}}{\mathrm{PbS}\left(\mathrm{s}\right)}+\underset{\mathrm{Lead}\mathrm{oxide}}{2\mathrm{PbO}\left(\mathrm{s}\right)}\to \underset{\mathrm{Lead}}{3\mathrm{Pb}\left(\mathrm{s}\right)}+\underset{\mathrm{Sulfur}\mathrm{dioxide}}{{\mathrm{SO}}_2\left(\mathrm{g}\right)}(\mathrm{self}-\mathrm{reduction}) \end{gathered}$$

Carbon reduction:

1. This Carbon reduction basically involves the reduction of substances, usually the metal oxides by the use of Carbon as a reducing agent.
2. Actually in this process the oxides of the metals which are less electropositive will get reduced by the very strong heating using coke or coal.
3. And it is used for the extraction of the metals such as: Iron, Copper, Tin etc.
4. Therefore, Carbon reduction of $\mathrm{Sn}$ is: $$\begin{gathered} \underset{\mathrm{Tin}\mathrm{oxide}}{{\mathrm{SnO}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}}{\mathrm{C}\left(\mathrm{s}\right)}\stackrel{∆}{\to }\underset{\mathrm{Tin}}{\mathrm{Sn}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)} \\ \underset{\mathrm{Tin}\mathrm{oxide}}{{\mathrm{SnO}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{monoxide}}{2\mathrm{CO}\left(\mathrm{s}\right)}\to \underset{\mathrm{Tin}}{\mathrm{Sn}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{2{\mathrm{CO}}_2\left(\mathrm{g}\right)} \end{gathered}$$

Hence, the correct option is (D): self reduction and carbon reduction respectively.