Question

Given below are two statements :
Statement I: Sphalerite is a sulphide ore of zinc and copper glance is a sulphide ore of copper.
Statement II: It is possible to separate two sulphide ores by adjusting proportion of oil to water or by using 'depressants' in a froth flotation method.

• A. Both Statement I and Statement II are true.
• B. Both Statement I and Statement II are false.
• C. Statement I is true but Statement II is false.
• D. Statement I is false but Statement II is true.

Hint:

Remember the names and formulas of important ores (like Sphalerite, Galena, Copper Glance, Bauxite, Hematite). For separation techniques, understand the underlying principle. Froth flotation is specific to sulphide ores and can be made selective using activators and depressants.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to evaluate the correctness of two statements related to metallurgy, specifically concerning sulphide ores and the froth flotation process.
Step 2: Detailed Explanation:
Analysis of Statement I:
- Sphalerite is a major ore of zinc. Its chemical formula is ZnS (zinc sulfide). So, it is a sulphide ore of zinc.
- Copper glance, also known as chalcocite, is an important ore of copper. Its chemical formula is Cu\(_2\)S (copper(I) sulfide). So, it is a sulphide ore of copper.
- Therefore, Statement I is true.
Analysis of Statement II:
- The froth flotation method is used for the concentration of sulphide ores. The principle is that sulphide ore particles are preferentially wetted by oil, while gangue particles are wetted by water.
- When two different sulphide ores are present in a sample (e.g., an ore containing both ZnS and PbS), they can be separated by a process called differential flotation.
- This is achieved by using reagents called 'depressants'. A depressant selectively prevents one type of sulphide ore from coming to the froth. For example, sodium cyanide (NaCN) is used as a depressant to separate ZnS from PbS. It forms a complex with zinc on the surface of ZnS, preventing it from being wetted by oil, while PbS forms the froth.
- Adjusting the proportion of oil to water is also a parameter that can be controlled to optimize the separation.
- Therefore, Statement II is also true.
Step 3: Final Answer:
Since both Statement I and Statement II are true, the correct option is (A).