See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Maximum pH Value in Water **Step 1: Understand pH and basicity** $$\text{pH} = -\log[H^+] \quad \text{or} \quad \text{pOH} = -\log[OH^-]$$ Maximum pH occurs when a solution is most basic (highest $[OH^-]$ concentration). **Step 2: Analyze each species** - **(A) $OH^-$**: Strong base — directly provides hydroxide ions; highly basic - **(B) $CH_3O^{\ominus}$** (methoxide ion): Conjugate base of $CH_3OH$ (very weak acid, $pK_a \approx 15.5$); strong base but less than $OH^-$ - **(C) $CH_3CH_2OH$**: Neutral alcohol; no significant $OH^-$ production - **(D) $CH_3OH$**: Weak acid; minimal ionization; nearly neutral **Step 3: Compare basicity strengths** The order of base strength: $$OH^- > CH_3O^{\ominus} > CH_3CH_2OH \approx CH_3OH$$ $OH^-$ is the strongest base because it is **already the hydroxide ion** and doesn't depend on dissociation equilibria. **Step 4: Conclusion** $OH^-$ produces the highest concentration of $[OH^-]$ ions, resulting in the maximum pH value. **Answer: (A) $OH^-$**