Which of the following does not contain a double bond?

Options

A. `CO_(2)`
B. `C_(2)H_(4)`
C. HCl
D. `O_(2)`

Explanation

To determine which of the given molecules does not contain a double bond, we need to analyze each option by looking at their structures and the types of bonds present.

### Step-by-Step Solution:

1. **Identify the Molecules**: We need to consider the given molecules. Let's assume the options are CO2, C2H4, and HCl.

2. **Analyze CO2 (Carbon Dioxide)**:
- Carbon (C) has 4 valence electrons.
- Oxygen (O) has 6 valence electrons.
- In CO2, carbon forms double bonds with two oxygen atoms to satisfy the octet rule.
- Structure: O=C=O (two double bonds).
- **Conclusion**: CO2 contains double bonds.

3. **Analyze C2H4 (Ethylene)**:
- Each carbon (C) has 4 valence electrons, and there are two carbon atoms.
- Each hydrogen (H) has 1 valence electron.
- In C2H4, the two carbon atoms share two pairs of electrons (double bond) and each carbon atom forms single bonds with two hydrogen atoms.
- Structure: H2C=CH2 (one double bond between the two carbon atoms).
- **Conclusion**: C2H4 contains a double bond.

4. **Analyze HCl (Hydrochloric Acid)**:
- Hydrogen (H) has 1 valence electron, and chlorine (Cl) has 7 valence electrons.
- In HCl, hydrogen forms a single bond with chlorine by sharing one pair of electrons.
- Structure: H-Cl (single bond).
- **Conclusion**: HCl does not contain a double bond.

5. **Final Answer**: Based on the analysis, the molecule that does not contain a double bond is **HCl**.