`X^(-)(aq)+AgNO_(3)tounderset("white ppt")(AgXdarr)`
White ppt of `AgX` dissolve in dil ammonia solution.Then `X` is

Explanation

To solve the problem, we need to identify the anion \( X^- \) that forms a white precipitate with silver nitrate (\( AgNO_3 \)) and dissolves in dilute ammonia solution.

### Step-by-Step Solution:

1. **Identify the Reaction**:
The reaction given is:
\[
X^-(aq) + AgNO_3 \rightarrow AgX(s)
...