Which amongst the following has a polar covalent bond?

Options

A. NaCl
B. `NH_(3)`
C. `O_(2)`
D. CaO

Answer

To determine which of the given compounds has a polar covalent bond, we can analyze each option based on the nature of the bonds formed between the atoms in the compounds. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
Let's assume the options provided are:
1. NaCl (Sodium Chloride)
2. NH₃ (Ammonia)
3. O₂ (Oxygen)
4. CaO (Calcium Oxide)

### Step 2: Analyze NaCl
- **NaCl** is formed from sodium (Na) and chlorine (Cl).
- Sodium donates an electron to chlorine, resulting in the formation of Na⁺ and Cl⁻ ions.
- The bond formed is an ionic bond due to the electrostatic attraction between the oppositely charged ions.
- **Conclusion**: NaCl does not have a polar covalent bond.

### Step 3: Analyze NH₃
- **NH₃** consists of nitrogen (N) and hydrogen (H).
- The N-H bonds involve the sharing of electrons, which is characteristic of covalent bonds.
- However, nitrogen is more electronegative than hydrogen, creating a dipole moment (partial positive charge on H and partial negative charge on N).
- **Conclusion**: NH₃ has polar covalent bonds.

### Step 4: Analyze O₂
- **O₂** is a diatomic molecule consisting of two oxygen atoms.
- The bond between the two oxygen atoms is formed by the equal sharing of electrons since both atoms have the same electronegativity.
- **Conclusion**: O₂ has a non-polar covalent bond.

### Step 5: Analyze CaO
- **CaO** is formed from calcium (Ca) and oxygen (O).
- Calcium donates two electrons to oxygen, forming Ca²⁺ and O²⁻ ions.
- The bond formed is ionic due to the transfer of electrons and the resulting electrostatic attraction.
- **Conclusion**: CaO does not have a polar covalent bond.

### Final Conclusion
Among the given options, **NH₃ (Ammonia)** is the only compound that has a polar covalent bond.