During metal extraction, which of the following metallurgical processes is specifically used to remove reducible metal oxides from a molten metal by using a wooden pole or similar reducing agent?

Introduction / Context:
In metallurgy, various refining processes are used to remove impurities from metals after their initial extraction from ore. Some impurities appear as oxides dissolved in the molten metal and can be removed by specific treatments. The process of poling is one such method, particularly used for refining metals like copper and tin. This question checks whether you can match the description of removing reducible oxides using a reducing agent with the correct metallurgical term.

Given Data / Assumptions:

• The goal is to remove reducible metal oxides from a molten metal.
• A wooden pole or similar material is introduced into the melt to act as a reducing agent.
• The options include liquation, cupellation, poling and electro refining.
• We assume standard descriptions of these processes from metallurgy texts.

Concept / Approach:
Poling involves stirring molten metal with green wood poles or other carbonaceous materials. The gases and carbon released reduce metal oxides present in the melt back to the metal, improving purity. This method is especially common in the refining of blister copper, where cuprous oxide impurities are reduced to copper metal. Liquation separates metals with different melting points, cupellation oxidises impurities like lead and removes them as oxides, and electro refining uses electrolytic cells to purify metals. The description in the question clearly aligns with poling, not with the other processes.

Step-by-Step Solution:
Step 1: Interpret the description: reducible oxides are being removed from molten metal by reduction, not by oxidation or electrolysis.Step 2: Recall that in poling, a wooden pole is inserted into the molten metal, and the released gases act as reducing agents.Step 3: Recognise that this reduces metal oxides, for example Cu2O, back to the metal, such as copper.Step 4: Compare with liquation, which relies on differential melting points and does not involve such reduction by wooden poles.Step 5: Cupellation involves strong oxidation in a furnace to remove base metals, especially in silver refining, and does not match the reducing description.Step 6: Electro refining uses electrical current and electrolyte solutions, which again is completely different from the described process.Step 7: Therefore, the process described is poling.

Verification / Alternative check:
As an alternative check, think specifically about copper refining. Blister copper contains copper oxide impurities that make the metal brittle. In the poling step, a wooden pole is thrust into the molten copper, releasing reducing gases that convert Cu2O into Cu and CO2. This is a classic textbook example and matches the question stem almost word for word. No such description appears when explaining liquation, cupellation or electro refining, reinforcing that poling is the correct answer.

Why Other Options Are Wrong:
Option a, liquation, is used to separate metals based on differences in melting point and is not focused on reducing oxides. Option b, cupellation, is an oxidative process used mainly in refining silver or lead by oxidising and removing impurities, not by reducing oxides. Option d, electro refining, uses an electrolytic cell to transfer pure metal from an impure anode to a cathode and does not rely on wooden poles or gaseous reduction. Therefore, these options do not match the reduction based process described.

Common Pitfalls:
Students may confuse poling with cupellation because both can appear in the context of refining, or they may think any purification process could fit the description. Another pitfall is to focus on terms like "refining" without paying attention to whether the process is oxidative or reductive. To avoid such mistakes, link specific keywords with each process: "wooden pole and reduction" with poling, "oxidation of lead" with cupellation and "electrolytic cell" with electro refining.

Final Answer:
The metallurgical process used to remove reducible oxides from molten metal by using a wooden pole as a reducing agent is called poling.