According to Werner's theory, how many types of valencies are shown by central metal atom?

Options

A. 1
B. 2
C. 3
D. 4

Answer

To solve the question regarding the types of valencies shown by a central metal atom according to Werner's theory, we can follow these steps:

### Step 1: Understand Werner's Theory
Werner's theory of coordination compounds introduced the concept of valency in central metal atoms. It distinguishes between two types of valencies.

### Step 2: Identify the Types of Valencies
According to Werner's theory, the two types of valencies are:
1. **Primary Valency**: This type of valency is associated with the ionization of the metal ion. It is satisfied by negative ions (anions) and is typically represented by ionic bonds.
2. **Secondary Valency**: This type of valency is associated with the coordination of ligands to the central metal atom. It involves the formation of coordinate covalent bonds, where the ligands donate electron pairs to the metal.

### Step 3: Conclusion
Based on the understanding of Werner's theory, we conclude that a central metal atom exhibits **two types of valencies**: primary and secondary.

### Final Answer
The correct answer is **2**.

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