Each of the three metals X,Y and Z were put in turn into aqueous solution of the salts of other two .
X + Salt of Y (or Z) = Y (or Z) + Salt of X.
Which observation is probably incorrect ?

Options

A. Y + Salt of X = No action observed
B. Y + Salt of Z = Z + Salt of Y
C. Z + Salt of X = X + Salt of Z
D. Z + Salf of Y = No action observed

Answer

To solve the problem, we need to analyze the given reactions involving metals X, Y, and Z and their respective salts. The key concept here is the reactivity of metals, which can be understood through the electrochemical series.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- The general reaction format is:
\[ \text{Metal} + \text{Salt of another metal} \rightarrow \text{Displaced metal} + \text{Salt of the first metal} \]
- This indicates that a more electropositive metal can displace a less electropositive metal from its salt solution.

2. **Analyzing Each Observation**:
- **Observation 1**: \( Y + \text{Salt of } X \rightarrow \text{No action observed} \)
- Since X is more electropositive than Y, this observation is correct.

- **Observation 2**: \( Y + \text{Salt of } Z \rightarrow Z + \text{Salt of } Y \)
- We do not have enough information about the relative reactivity of Y and Z. This observation cannot be confirmed as correct or incorrect without additional data.

- **Observation 3**: \( Z + \text{Salt of } X \rightarrow X + \text{Salt of } Z \)
- Since X is more electropositive than Z, Z cannot displace X from its salt. This observation is incorrect.

- **Observation 4**: \( Z + \text{Salt of } Y \rightarrow \text{No action observed} \)
- Similar to observation 2, we do not have enough information to confirm this observation.

3. **Conclusion**:
- The incorrect observation is **Observation 3**: \( Z + \text{Salt of } X \rightarrow X + \text{Salt of } Z \) because Z cannot displace X from its salt.

### Final Answer:
The observation that is probably incorrect is:
**Observation 3**: \( Z + \text{Salt of } X \rightarrow X + \text{Salt of } Z \).