Which of the following methods is NOT used to extract metals that are placed in the middle of the reactivity series from their ores?

Appeared in: RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

Explanation

This method is incorrect because carbon is not an effective reducing agent for metal sulphides directly.
Thermodynamically, carbon has a much higher affinity for oxygen than for sulphur, making the direct reduction of a sulphide ore inefficient.
Sulphide ores must first be converted into their corresponding oxides through a process called roasting before they can be reduced by carbon.

Option A: This is a valid method used for the extraction of metals from their carbonate ores.
Option B: This is a valid, though less common, method used when carbon reduction is not suitable.
Option D: This is the standard and correct method for extracting metals from their sulphide ores.

Visual 1: Flowchart: Illustrating the different metallurgical processes (roasting, calcination, reduction) for extracting metals from sulphide and carbonate ores.
Visual 2: Diagram: Showing a blast furnace used for the reduction of iron oxide with carbon (smelting), a key process for metals in the middle of the reactivity series.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Metallurgy: Extraction of metals from the middle of the reactivity series as background academic context rather than a clinical decision trigger.
While this is a general chemistry topic, understanding chemical reactivity is foundational in healthcare.
The principle of using a more reactive substance to displace another is analogous to chelation therapy for heavy metal poisoning (e.g., lead, mercury). A chelating agent forms a more stable bond with the toxic metal, displacing it from biological molecules and allowing it to be excreted.
What if the metal was highly reactive (e.g., Sodium, Potassium)? Then, reduction with carbon would not work. Electrolysis of their molten salts would be the required method, as these metals are too reactive to be displaced by carbon.

How to Approach the Question

First, identify the core of the question: it's about the extraction methods for metals in the 'middle of the reactivity series' (like Zn, Fe, Pb).
Second, pay close attention to the negative keyword 'NOT'. This means you are looking for the one option that is an incorrect or unused procedure.
Third, recall the standard metallurgical steps for these metals. Their ores (sulphides, carbonates) are not reduced directly. They are first converted into oxides.
Fourth, evaluate each option: Roasting is for sulphide ores (to make oxides). Calcination is for carbonate ores (to make oxides). Reduction with carbon is the common next step for these oxides. Displacement is also a valid, though specific, method.
Finally, identify the option that breaks this rule. Option C suggests a direct reduction of a sulphide ore with carbon, skipping the essential conversion-to-oxide step (roasting). This makes it the incorrect procedure and thus the correct answer.

Concept Tested & Keywords

Concept Tested: Metallurgy: Extraction of metals from the middle of the reactivity series.
Stem keywords: extract metals, middle of the reactivity series, ores
Lead-in keywords: NOT
Negative lead-in flag: The question asks for the method that is NOT used.

QeDDTQETnOvLQuFXlyz3W4

Practise the full RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.