Identify the molecule with a single covalent bond.

Options

A. `CO_2`
B. CO
C. `CH_4`
D. `N_2`

Explanation

To identify the molecule with a single covalent bond, we will analyze the bonding in various molecules.

**Step 1: Understand the concept of covalent bonds**
- A covalent bond is formed when two atoms share electrons. A single covalent bond involves the sharing of one pair of electrons.

**Step 2: Identify the electronic configuration of the relevant elements**
- Carbon (C): Atomic number 6 → Electronic configuration: 1s² 2s² 2p²
- Nitrogen (N): Atomic number 7 → Electronic configuration: 1s² 2s² 2p³
- Oxygen (O): Atomic number 8 → Electronic configuration: 1s² 2s² 2p⁴
- Hydrogen (H): Atomic number 1 → Electronic configuration: 1s¹

**Step 3: Determine how many electrons each element needs to share to complete its octet or duplet**
- Carbon needs to share 4 electrons to complete its octet.
- Nitrogen needs to share 3 electrons to complete its octet.
- Oxygen needs to share 2 electrons to complete its octet.
- Hydrogen needs to share 1 electron to complete its duplet.

**Step 4: Analyze the bonding in different molecules**
- **CO2 (Carbon Dioxide)**: Carbon shares 4 electrons (2 double bonds with oxygen). This forms double bonds, not single.
- **CO (Carbon Monoxide)**: Carbon and oxygen share 3 electrons (1 double bond and a coordinate bond). This forms a triple bond, not single.
- **CH4 (Methane)**: Carbon shares 4 electrons with 4 hydrogen atoms (1 electron each). This forms 4 single covalent bonds.
- **N2 (Nitrogen Gas)**: Each nitrogen shares 3 electrons, forming a triple bond.

**Step 5: Conclusion**
- The only molecule that forms single covalent bonds is **CH4 (Methane)**.

**Final Answer: CH4 (Methane) is the molecule with a single covalent bond.**

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