which of the following compounds on reaction with NaOH and
`H_(2)O_(2)` gives yellow colour ?

Options

A. `Zn(OH)_(2)`
B. `Cr(OH)_(3)`
C. `AI(OH)_(3)`
D. None of these.

Explanation

To solve the question of which compound reacts with NaOH and H₂O₂ to give a yellow color, we can follow these steps:

### Step 1: Identify the Compounds
We need to consider the potential compounds that could react with sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂). The compounds mentioned in the question are likely to be metal hydroxides or oxides.

### Step 2: Understand the Role of H₂O₂
Hydrogen peroxide acts as an oxidizing agent in this reaction. It can oxidize certain metal ions to higher oxidation states, which may lead to the formation of colored compounds.

### Step 3: Analyze the Oxidation States
- **Zinc (Zn)**: In its compounds, zinc typically exists in the +2 oxidation state. It cannot be oxidized further since its maximum oxidation state is +2.
- **Aluminum (Al)**: Aluminum typically exists in the +3 oxidation state. It also cannot be oxidized further.
- **Chromium (Cr)**: Chromium can exist in multiple oxidation states, including +3, +4, and +6. The +3 oxidation state can be oxidized to +6.

### Step 4: Reaction of Chromium Hydroxide
When chromium hydroxide (Cr(OH)₃) reacts with NaOH and H₂O₂, it can be oxidized to sodium chromate (Na₂CrO₄):
\[ \text{Cr(OH)}_3 + \text{NaOH} + \text{H}_2\text{O}_2 \rightarrow \text{Na}_2\text{CrO}_4 + \text{H}_2\text{O} \]

### Step 5: Balancing the Reaction
The balanced reaction can be written as:
\[ 4 \text{NaOH} + 3 \text{H}_2\text{O}_2 \rightarrow 2 \text{Na}_2\text{CrO}_4 + 8 \text{H}_2\text{O} \]

### Step 6: Identify the Color of the Product
Sodium chromate (Na₂CrO₄) is known to be a yellow-colored compound. Thus, the reaction of chromium compounds with NaOH and H₂O₂ results in a yellow solution.

### Conclusion
The compound that reacts with NaOH and H₂O₂ to give a yellow color is chromium hydroxide, leading to the formation of sodium chromate.

### Final Answer
The correct answer is **B (Chromium compound)**.

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