Final answer:
The weakest bond among C.I (carbon-iodine), N=N (nitrogen double bond), Na−Br (sodium-bromine ionic bond), and C=O (carbon-oxygen double bond) is the carbon-iodine bond (C-I) because of its lower bond dissociation energy.
Step-by-step explanation:
To choose the weakest bond among the given options, we should consider both bond type (ionic or covalent) and bond strength (single, double, or triple bonds). Ionic bonds can be strong due to the electrostatic attraction between ions, but when comparing to covalent bonds, molecular interactions and chemical contexts can contribute to variations in bond strength.
C.I likely refers to a carbon-iodine bond. N=N is a nitrogen double bond, which is relatively strong due to the sharing of two electron pairs. Na-Br represents a sodium-bromine ionic bond, and C=O denotes a carbon-oxygen double bond, which is known for its strong bond energy.