Covalent solid among the following is

Options

A. solid Ar
B. MgO
C. Fe
D. BN

Answer

To determine which of the given options is a covalent solid, we need to analyze the properties of each substance listed:

1. **Identify the Options**: The options provided are:
- Solid Argon (Ar)
- Magnesium Oxide (MgO)
- Iron (Fe)
- Boron Nitride (BN)

2. **Understanding Covalent Solids**: Covalent solids are characterized by a network of covalent bonds throughout the structure. This means that each atom is bonded to its neighboring atoms via strong covalent bonds, forming a continuous network. Examples of covalent solids include diamond and boron nitride.

3. **Analyzing Each Option**:
- **Solid Argon (Ar)**: Argon is a noble gas and exists as a monoatomic gas under standard conditions. In solid form, it does not form covalent bonds but rather exists in a simple cubic lattice held together by weak van der Waals forces. Therefore, it is not a covalent solid.

- **Magnesium Oxide (MgO)**: Magnesium oxide is an ionic compound. It consists of magnesium ions (Mg²⁺) and oxide ions (O²⁻) held together by ionic bonds, not covalent bonds. Hence, it is not a covalent solid.

- **Iron (Fe)**: Iron is a metallic solid. It consists of metal atoms arranged in a metallic lattice, where the atoms share a "sea of electrons." This does not qualify as a covalent solid.

- **Boron Nitride (BN)**: Boron nitride can exist in different forms, one of which is hexagonal boron nitride (h-BN), which has a layered structure similar to graphite. In this form, boron and nitrogen atoms are covalently bonded in a planar structure, making it a covalent solid.

4. **Conclusion**: Among the options provided, Boron Nitride (BN) is the only covalent solid due to its network of covalent bonds.

**Final Answer**: The covalent solid among the following is Boron Nitride (BN).

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