Each of the three metals X,Y and Z were put in turn into aqueous solution of the 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 reactions involving three metals X, Y, and Z, and their respective salts. The key concept here is the reactivity series of metals, which helps us determine whether one metal can displace another from its salt solution.

### Step-by-Step Solution:

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

2. **Analyze Each Statement**:
- **Statement 1**: \( Y + \text{Salt of } X \rightarrow \text{No action observed} \)
- Since X is more reactive than Y, Y cannot displace X from its salt. This statement is **correct**.

- **Statement 2**: \( Y + \text{Salt of } Z \rightarrow Z + \text{Salt of } Y \)
- Here, Y is displacing Z from its salt. This implies that Y is more reactive than Z. This statement is **correct** if Y is indeed more reactive than Z.

- **Statement 3**: \( Z + \text{Salt of } X \rightarrow X + \text{Salt of } Z \)
- In this case, Z is attempting to displace X from its salt. Since X is more reactive than Z, Z cannot displace X. This statement is **incorrect**.

- **Statement 4**: \( Z + \text{Salt of } Y \rightarrow \text{No action observed} \)
- Since Y is more reactive than Z, Z cannot displace Y from its salt. This statement is **correct**.

3. **Conclusion**: The incorrect observation is from Statement 3, where Z is trying to displace X, which is not possible due to X's higher reactivity.

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

---