Consider the following reactions :
`2XS+3O_(2)overset(Delta)to 2XO+2SO_(2)`
`2XO+XS overset(Delta)to 3' X'+SO_(2)`
Then 'X' can not be :

Options

A. Hg
B. Pb
C. Zn
D. None

Explanation

To solve the question, we need to analyze the given reactions and determine which metal 'X' cannot be based on the self-reduction process of sulfides.

### Step-by-Step Solution:

1. **Identify the Reactions**:
- The first reaction is:
\[ 2XS + 3O_2 \overset{\Delta}{\rightarrow} 2XO + 2SO_2 \]
- The second reaction is:
\[ 2XO + XS \overset{\Delta}{\rightarrow} 3X' + SO_2 \]

2. **Understand the Process**:
- The first reaction indicates that the metal sulfide (XS) is being roasted in the presence of oxygen (O2) to produce metal oxide (XO) and sulfur dioxide (SO2).
- The second reaction shows the reduction of the metal oxide (XO) back to the metal (X') using the original metal sulfide (XS).

3. **Identify Metals that Undergo Self-Reduction**:
- Self-reduction is a process where certain metal sulfides can reduce themselves to metals upon roasting. The known sulfides that can undergo self-reduction are:
- Lead sulfide (PbS)
- Mercury sulfide (HgS)
- Copper sulfide (CuS)

4. **Evaluate the Options**:
- We need to determine which metal 'X' cannot be. The options typically include metals like Lead (Pb), Mercury (Hg), Copper (Cu), and Zinc (Zn).
- From our knowledge, we see that:
- PbS, HgS, and CuS can undergo self-reduction.
- However, Zinc sulfide (ZnS) does not undergo self-reduction.

5. **Conclusion**:
- Therefore, the metal 'X' cannot be Zinc (Zn) because it does not participate in the self-reduction process.

### Final Answer:
X cannot be: **Zinc (Zn)**.