Which of these has a triple covalent bond?

Options

A. `PH_(3)`
B. `CO_(2)`
C. `AlCl_(3)`
D. `C_(2)H_(2)`

Explanation

To determine which of the given compounds has a triple covalent bond, we will analyze each compound by drawing their Lewis structures and examining the types of bonds formed.

### Step-by-Step Solution:

1. **Identify the Compounds**: We need to analyze the following compounds: Ph3 (Phosphorus trihydride), CO2 (Carbon dioxide), AlCl3 (Aluminum chloride), and C2H2 (Ethylene).

2. **Draw the Lewis Structure for Ph3**:
- Phosphorus (P) has 5 valence electrons.
- Each Hydrogen (H) has 1 valence electron.
- Phosphorus forms single bonds with 3 Hydrogen atoms.
- Total electrons used: 3 (1 for each H) + 2 remaining on P (lone pair).
- **Conclusion**: Ph3 has only single bonds; no triple bond is present.

3. **Draw the Lewis Structure for CO2**:
- Carbon (C) has 4 valence electrons, and Oxygen (O) has 6 valence electrons.
- To complete the octet, each Oxygen forms a double bond with Carbon.
- Total bonds: 2 double bonds (one with each O).
- **Conclusion**: CO2 has double bonds; no triple bond is present.

4. **Draw the Lewis Structure for AlCl3**:
- Aluminum (Al) has 3 valence electrons, and Chlorine (Cl) has 7 valence electrons.
- Aluminum forms 3 single bonds with 3 Chlorine atoms.
- Total bonds: 3 single bonds.
- **Conclusion**: AlCl3 has only single bonds; no triple bond is present.

5. **Draw the Lewis Structure for C2H2**:
- Each Carbon (C) has 4 valence electrons, and each Hydrogen (H) has 1 valence electron.
- Each Carbon forms a single bond with one Hydrogen and a triple bond with the other Carbon.
- Total bonds: 1 single bond (C-H) and 1 triple bond (C≡C).
- **Conclusion**: C2H2 has a triple bond between the two Carbon atoms.

6. **Final Answer**: Based on the analysis, the compound that contains a triple covalent bond is **C2H2 (Ethylene)**.