Final answer:
The molecule among the options that has only a single bond is Cl2 (chlorine gas), as it consists of two chlorine atoms sharing one pair of electrons in a single covalent bond, the correct option is E).
Step-by-step explanation:
The student has asked which of the listed molecules only has a single bond. Examining each molecule:
- O2 has a double bond.
- CO has a triple bond.
- CN- has a triple bond (not considering the negatively charged ion).
- N2 has a triple bond.
- Cl2, which consists of two chlorine atoms, forms a single covalent bond between them.
Therefore, the molecule that only has a single bond is Cl2 (chlorine gas).