Q17 / 150 · MHT CET 2026 (15 April Shift 2) · Chemistry
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$[\text{Zn}(\text{H}_2\text{O})_3]^{2-}$
- Correct answerC$[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^{+}$
- D$[\text{Zn}(\text{H}_2\text{O})\text{H}]^{3+}$
Solution
According to the Bronsted-Lowry theory, a conjugate base is formed when an acid loses a proton ($\text{H}^{+}$).
The given species is $[\text{Zn}(\text{H}_2\text{O})_4]^{2+}$.
Removing a proton ($\text{H}^{+}$) from one of the coordinated water molecules gives:
$[\text{Zn}(\text{H}_2\text{O})_4]^{2+} \rightarrow [\text{Zn}(\text{H}_2\text{O})_3(\text{OH})]^{+} + \text{H}^{+}$
Thus, the conjugate base is $[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^{+}$.
Answer: $[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^{+}$
The given species is $[\text{Zn}(\text{H}_2\text{O})_4]^{2+}$.
Removing a proton ($\text{H}^{+}$) from one of the coordinated water molecules gives:
$[\text{Zn}(\text{H}_2\text{O})_4]^{2+} \rightarrow [\text{Zn}(\text{H}_2\text{O})_3(\text{OH})]^{+} + \text{H}^{+}$
Thus, the conjugate base is $[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^{+}$.
Answer: $[\text{Zn}(\text{H}_2\text{O})_3\text{OH}]^{+}$
Hence, the correct answer is option: 'C'.