The structures of beryllium chloride in the solid state and vapur phase, respectively, are:

Options

A. dimeric and chain
B. dimeric and dimeric
C. chain and chain
D. chain and dimeric

Explanation

To determine the structures of beryllium chloride (BeCl2) in the solid state and vapor phase, we can follow these steps:

### Step 1: Identify the Chemical Formula
The chemical formula for beryllium chloride is BeCl2. This indicates that each beryllium atom is bonded to two chloride ions.

**Hint:** Remember that the subscripts in a chemical formula indicate the number of atoms of each element in the compound.

### Step 2: Analyze the Vapor Phase Structure
In the vapor phase, beryllium chloride exists in a dimeric form. This means that two BeCl2 units combine to form a dimer. The structure can be represented as:

- BeCl2 + BeCl2 → (Be2Cl4)

In this dimeric form, the beryllium atoms are connected through coordination bonds with the chloride ions.

**Hint:** Dimeric structures often form in the vapor phase due to the tendency of molecules to pair up for stability.

### Step 3: Analyze the Solid State Structure
In the solid state, beryllium chloride adopts a chain structure. This means that the BeCl2 units are linked together in a long chain, with alternating beryllium and chloride ions. The structure can be represented as:

- Be-Cl-Be-Cl-Be-Cl...

This chain continues, forming a polymeric structure.

**Hint:** Solid-state structures often exhibit different bonding arrangements compared to their gaseous counterparts due to stronger intermolecular forces.

### Step 4: Conclusion
Based on the analysis:
- In the vapor phase, beryllium chloride exists in a **dimeric form**.
- In the solid state, beryllium chloride exists in a **chain form**.

Thus, the correct answer is: **Dimeric in vapor phase and chain in solid state.**

**Final Answer:** The structures of beryllium chloride in the solid state and vapor phase are dimeric and chain, respectively.