Fill in the blanks by choosing the appropriate word/words from those given in the brackets: (double salts, complex compounds, uni, bi, six, four, three, coordination, linkage, imperfect, perfect, normal, penetrating, central ion, chelating, Werner, Pauling)
The addition compounds which retain their identity in solution are called......

Explanation

To solve the question, we need to fill in the blank with the appropriate term from the provided options. The sentence reads: "The addition compounds which retain their identity in solution are called......"

### Step-by-Step Solution:

1. **Understanding the Question**: We need to identify what type of compounds retain their identity when dissolved in a solution.

2. **Analyzing the Options**: The options provided include:
- double salts
...