Question

Identify from following the conjugate base of \([\text{Zn}(\text{H}_2\text{O})_4]^{2+}\)

• A. \([\text{Zn}(\text{H}_2\text{O})_4]^{2-}\,\text{NH}_3\)
• B. \([\text{Zn}(\text{H}_2\text{O})_3]^{2-}\)
• C. \([\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^+\)
• D. \([\text{Zn}(\text{H}_2\text{O})\text{H}]^{3+}\)

Hint:

A conjugate base forms by removing one H+ from the acid, leaving charge one unit lower.

Answer 1

The Correct Option is C

Step 1: Rule
Conjugate base = acid minus $\text{H}^+$. The charge becomes one unit less positive.

Step 2: Apply
From $2+$ the charge falls to $1+$, and one water turns into hydroxide in the coordination sphere.

Step 3: Match
Only $[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^+$ has charge $+1$ and is made by removing one proton, so (C). Option (D) has gained a proton.

Final Answer:
Option (C). \[ \boxed{[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^+} \]