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When sodium hydroxide is introduced into an aqueous Zn2+ solution, a white precipitate forms, and this precipitate dissolves when more NaOH is added. In such a solution, zinc is present in the:

1. both cationic and anionic forms
2. no zinc remains in the solution
3. cationic form
4. anionic form

Correct answer: anionic form

Solution

The correct option is right because when excess NaOH is added to the solution, it forms a soluble zincate complex, indicating that zinc is present in anionic form as zincate ions (Zn(OH)4²-), rather than remaining solely as cations.

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