Ammonium hydroxide is a weak alkali which dissociates partially to furnish............ `OH^(-)` ions precipitate...............metal hydroxides.

Options

A. Sufficient, Soluble
B. Insufficient, Insoluble
C. Sufficient, Insoluble
D. Insufficient, Soluble

Explanation

To solve the question, we need to understand the behavior of ammonium hydroxide (NH4OH) as a weak alkali and its interaction with metal ions. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding Ammonium Hydroxide
Ammonium hydroxide is a weak alkali that partially dissociates in water to produce hydroxide ions (OH⁻). The dissociation can be represented as:
\[ \text{NH}_4\text{OH} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]

### Step 2: Hydroxide Ion Production
Since ammonium hydroxide is a weak base, it does not completely dissociate. This means that the concentration of OH⁻ ions produced is limited compared to strong bases.

### Step 3: Precipitation of Metal Hydroxides
The hydroxide ions (OH⁻) can react with certain metal ions to form metal hydroxides. The solubility of these metal hydroxides varies. Some metal hydroxides are insoluble and will precipitate out of the solution when formed.

### Step 4: Example of Metal Hydroxide Formation
For instance, when ammonium hydroxide reacts with zinc chloride (ZnCl₂), zinc hydroxide (Zn(OH)₂) is formed:
\[ \text{ZnCl}_2 + 2 \text{NH}_4\text{OH} \rightarrow \text{Zn(OH)}_2 \downarrow + 2 \text{NH}_4\text{Cl} \]

Here, Zn(OH)₂ is a precipitate because it is insoluble in water.

### Step 5: Conclusion
Thus, ammonium hydroxide partially dissociates to furnish hydroxide ions (OH⁻), which can precipitate insoluble metal hydroxides when they react with certain metal ions.

### Final Answer
Ammonium hydroxide is a weak alkali that partially dissociates to furnish **insufficient** OH⁻ ions, which can precipitate **insoluble** metal hydroxides.

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