The reversible reaction
`[Cu(NH_(3))_(4)]^(2+)+SO_(3)^(2-)hArr[Cu(NH_(3))_(3)SO_(3)]+NH_(3)`
is at equilibrium. What would not happen if ammonia is added -

Options

A. `[SO_(3)^(2-)]` would increase
B. `[Cu(NH_(3))_(3)SO_(3)]` would increase
C. The value of equilibrium constant would not change
D. `[Cu(NH_(3))_(4)]^(2+)` would increase

Answer

To solve the problem step by step, we will analyze the given reversible reaction and apply Le Chatelier's principle to understand the effects of adding ammonia.

### Step-by-Step Solution:

1. **Identify the Reaction**:
The reversible reaction given is:
\[ [Cu(NH_3)_4]^{2+} + SO_3^{2-} \rightleftharpoons [Cu(NH_3)_3SO_3] + NH_3 \]

2. **Understand the Equilibrium**:
In this reaction, we have a complex ion on the left side, which is in equilibrium with a different complex and ammonia on the right side.

3. **Effect of Adding Ammonia**:
When ammonia (NH₃) is added to the system, it increases the concentration of one of the products (NH₃). According to Le Chatelier's principle, if the concentration of a product is increased, the system will shift to the left (backward direction) to counteract this change and re-establish equilibrium.

4. **Determine the Direction of Shift**:
The addition of ammonia will cause the equilibrium to shift to the left, which means that the concentration of the reactants will increase, and the concentration of the products will decrease.

5. **Analyze the Options**:
Now, let's evaluate the options given in the question:
- **Option 1**: Concentration of SO₃ would increase.
- This is incorrect because the reaction shifts left, leading to a decrease in the concentration of SO₃.
- **Option 2**: Concentration of the complex would increase.
- This is correct as the reaction shifts left, forming more of the complex.
- **Option 3**: The value of the equilibrium constant would not change.
- This is incorrect because the equilibrium constant is only affected by temperature, not by concentration changes.
- **Option 4**: The concentration of NH₃ would increase.
- This is correct since we are adding NH₃.

6. **Conclusion**:
The option that states what would not happen if ammonia is added is:
- **Concentration of SO₃ would increase**.

### Final Answer:
The correct answer is: **Concentration of SO₃ would increase**.