Give IUPAC name of : `COOH-COOH`.

Explanation

To determine the IUPAC name of the compound `COOH-COOH`, follow these steps:

### Step 1: Identify the Structure
The compound consists of two carbon atoms, each bonded to a carboxylic acid group (–COOH). The structure can be represented as:
```
O
||
H-C-C-H
| |
O O
```

### Step 2: Count the Carbon Atoms
There are a total of 2 carbon atoms in the longest carbon chain.

### Step 3: Determine the Functional Groups
Both ends of the carbon chain have a carboxylic acid group (–COOH).

### Step 4: Name the Carbon Chain
The longest carbon chain has 2 carbon atoms, which corresponds to the prefix "ethane".

### Step 5: Identify the Position of Functional Groups
Since both carboxylic acid groups are attached to the first and second carbon atoms, we denote their positions as 1 and 2.

### Step 6: Use the Correct Suffix
For carboxylic acids, the suffix is "oic acid". Since there are two carboxylic acid groups, we use the prefix "dioic" to indicate two such groups.

### Step 7: Combine the Information
Putting it all together, the IUPAC name of the compound is:
**Ethane-1,2-dioic acid**

### Final Answer
The IUPAC name of `COOH-COOH` is **Ethane-1,2-dioic acid**.

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