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`
Q. Chloride compound of which element is hypovalent?

Options

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

Explanation

To solve the question regarding which element's chloride compound is hypovalent among the elements P, Q, R, and S from the 3rd period of the p-block, we can follow these steps:

### Step 1: Identify the Elements in the 3rd Period of the p-Block
The elements in the 3rd period of the periodic table are:
- Aluminium (Al) - Metal
- Silicon (Si) - Non-metal
- Phosphorus (P) - Non-metal
- Sulfur (S) - Non-metal
- Chlorine (Cl) - Non-metal

### Step 2: Understand the Concept of Hypovalency
Hypovalent refers to a species that has less than eight electrons in its valence shell, meaning its octet is not complete.

### Step 3: Analyze the Given Order of Electronegativity
The order of electronegativity provided is:
\[ P < Q < R < S \]
This indicates that P has the lowest electronegativity and S has the highest.

### Step 4: Identify the Metal and Non-Metals
From the elements listed:
- The metal is Aluminium (Al).
- The non-metals are Silicon (Si), Phosphorus (P), Sulfur (S), and Chlorine (Cl).

### Step 5: Determine the Chloride Compounds
- Aluminium forms Aluminium chloride (AlCl₃).
- Silicon forms Silicon chloride (SiCl₄).
- Phosphorus forms Phosphorus trichloride (PCl₃) or Phosphorus pentachloride (PCl₅).
- Sulfur forms Sulfur dichloride (SCl₂) or Sulfur tetrachloride (SCl₄).
- Chlorine forms Chlorine chloride (Cl₂).

### Step 6: Analyze the Valence Electrons in Aluminium Chloride
Aluminium (Al) has 3 valence electrons. When it forms AlCl₃:
- Each chlorine atom contributes 1 electron to complete its octet.
- Aluminium shares its 3 electrons with 3 chlorine atoms.

Thus, in AlCl₃, Aluminium effectively has only 6 electrons in its valence shell (3 of its own and 3 shared), making it hypovalent.

### Step 7: Identify the Element Corresponding to P
Since P has the lowest electronegativity and corresponds to Aluminium, we conclude that:
- The chloride compound of Aluminium (AlCl₃) is hypovalent.

### Final Answer
The chloride compound of the element P (Aluminium) is hypovalent.

---