Softening of lead means:

Options

A. conversion of lead to `PbO`
B. conversion of lead to `Pb_(3)O_(4)`
C. removal of impurities (metallic) from lead
D. washing lead with `HNO_(3)` followed by alkali solution

Answer

To answer the question "Softening of lead means:", we need to analyze the process involved in the softening of lead, particularly in the context of refining lead.

### Step-by-Step Solution:

1. **Understanding Softening of Lead**:
- Softening of lead refers to a process that occurs during the refining of lead. It is essential to understand that lead, in its raw form, may contain various impurities that can affect its properties.

2. **Refining Process**:
- The refining of lead involves several steps aimed at purifying the metal. One of the key objectives during this process is to remove impurities that are present in the lead.

3. **Impurities in Lead**:
- The impurities in lead can include other metals and non-metallic substances. These impurities can alter the physical and chemical properties of lead, making it less desirable for certain applications.

4. **Softening Mechanism**:
- The softening of lead specifically refers to the removal of these metallic impurities. This is typically achieved through chemical processes, such as washing the lead with nitric acid (HNO3) followed by treatment with an alkali solution. This process helps in dissolving and separating the impurities from the pure lead.

5. **Conclusion**:
- Therefore, the correct interpretation of "softening of lead" is the removal of metallic impurities from lead. This aligns with the context of refining lead, which is aimed at enhancing the purity and quality of the metal.

### Final Answer:
Softening of lead means the removal of metallic impurities from lead.