Name one reagent or one operation to distinguish between:
`Be(OH)_(2)` and `Ba(OH)_(2)`

Explanation

To distinguish between beryllium hydroxide, \( \text{Be(OH)}_2 \), and barium hydroxide, \( \text{Ba(OH)}_2 \), we can use sodium hydroxide (NaOH) as a reagent. Here’s a step-by-step explanation of the process:

### Step 1: Understand the Properties of the Hydroxides
- **Beryllium Hydroxide (\( \text{Be(OH)}_2 \))**: It is amphoteric, meaning it can react with both acids and bases. It is soluble in excess sodium hydroxide.
- **Barium Hydroxide (\( \text{Ba(OH)}_2 \))**: It is a strong base and is not amphoteric. It is insoluble in excess sodium hydroxide.

### Step 2: Prepare the Sample
- Take a small amount of each hydroxide: \( \text{Be(OH)}_2 \) and \( \text{Ba(OH)}_2 \).
...