`CrO_(3)` dissolves in aqueous NaOH to give:

Options

A. `Cr_(2)O_(7)^(2-)`
B. `CrO_(4)^(2-)`
C. `Cr(OH)_(3)`
D. `Cr(OH)_(2)`

Answer

To solve the question of what CrO₃ dissolves in aqueous NaOH to give, we can follow these steps:

### Step 1: Identify the Reactants
We have two reactants:
- Chromium trioxide (CrO₃)
- Aqueous sodium hydroxide (NaOH)

### Step 2: Determine the Nature of the Reactants
- CrO₃ is known to be acidic.
- NaOH is a strong base.

### Step 3: Predict the Reaction
When an acidic oxide (like CrO₃) reacts with a base (like NaOH), a salt and water are typically formed.

### Step 4: Write the Reaction Equation
The reaction can be represented as:
\[ \text{CrO}_3 + 2 \text{NaOH} \rightarrow \text{Na}_2\text{CrO}_4 + \text{H}_2\text{O} \]

### Step 5: Identify the Product
From the reaction, we can see that the product formed is sodium chromate (Na₂CrO₄).

### Step 6: Break Down the Product into Ions
When sodium chromate (Na₂CrO₄) dissolves in water, it dissociates into its ions:
\[ \text{Na}_2\text{CrO}_4 \rightarrow 2 \text{Na}^+ + \text{CrO}_4^{2-} \]

### Step 7: Conclusion
The chromate ion formed is \(\text{CrO}_4^{2-}\). Therefore, the correct answer to the question is option 2: \(\text{CrO}_4^{2-}\).

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