Rank the following in order of increasing base strength (weakest to strongest).
OI⁻      OCl⁻      OBr⁻

• A. OI⁻ < OCl⁻ < OBr⁻
• B. OCI⁻ < Ol⁻ < OBr⁻
• C. OCl⁻ < OBr⁻ < OI⁻
• D. they are equally basic
• E. can't tell based on structures

Answer: (C)

Verified step by step guidance

1. Identify the chemical species involved: OI^-, OCl^-, and OBr^-. These are all hypohalite ions, where the halogen is bonded to an oxygen atom.
2. Understand the concept of base strength: A base is stronger if it can more readily accept a proton (H⁺). In the context of these ions, the base strength is influenced by the stability of the conjugate acid formed after accepting a proton.
3. Consider the electronegativity of the halogens: Electronegativity affects the stability of the conjugate acid. The more electronegative the halogen, the more stable the conjugate acid, and thus the weaker the base. The order of electronegativity for the halogens is: Cl > Br > I.
4. Apply the concept of electronegativity to rank the bases: Since Cl is the most electronegative, OCl^- will form the most stable conjugate acid, making it the weakest base. Conversely, OI^- will form the least stable conjugate acid, making it the strongest base.
5. Rank the bases in order of increasing strength: OCl^- (weakest) < OBr^- < OI^- (strongest).