If P, Q, R and S are elements of 3rd period of p-block in modern periodic table, among these one element is metal and rest are non-metals and their order of electronegativity is given as:
`P lt Q lt R lt S`
Which element is expected to form amphoteric oxide?

Options

A. P
B. Q
C. R
D. S

Explanation

To solve the question, we need to identify which element among P, Q, R, and S is expected to form an amphoteric oxide.

### Step-by-Step Solution:

1. **Identify the Elements in the 3rd Period of the p-block:**
The elements in the 3rd period of the p-block are:
- Aluminium (Al) - Metal
- Silicon (Si) - Non-metal
- Phosphorus (P) - Non-metal
- Sulfur (S) - Non-metal
- Chlorine (Cl) - Non-metal
- Argon (Ar) - Noble gas (not considered here)

Since the question states that one element is a metal and the rest are non-metals, the metal in the 3rd period is Aluminium (Al).

2. **Understand the Order of Electronegativity:**
The order of electronegativity given is:
\( P < Q < R < S \).
This indicates that P has the lowest electronegativity and S has the highest.

3. **Relate Electronegativity to Oxide Formation:**
- Metals typically form basic oxides.
- Non-metals typically form acidic oxides.
- Amphoteric oxides can react with both acids and bases.

4. **Identify the Amphoteric Oxide:**
Among the elements listed, Aluminium (Al) is known to form an amphoteric oxide, which is Aluminium oxide (Al₂O₃). This oxide can react with both acids and bases, thus qualifying as amphoteric.

5. **Conclusion:**
Since Aluminium is the only metal in the 3rd period and it forms an amphoteric oxide, we conclude that:
- The element expected to form an amphoteric oxide is **P (Aluminium)**.

### Final Answer:
The element expected to form an amphoteric oxide is **P (Aluminium)**.

---