An element of 3d-transition series two oxidation states x and y, differ by two units then:

Options

A. compounds in oxidation state x are ionic if `xgty`
B. compounds in oxidation state x are ionic if `xlty`
C. compounds in oxidation state y are covalents if `xlty`
D. compounds in oxidation state y are covalents if `xgty`

Answer

To solve the question regarding the oxidation states of an element in the 3d-transition series, we need to analyze the properties of the compounds formed by these oxidation states. The question states that two oxidation states, \(X\) and \(Y\), differ by two units. We will denote \(Y = X + 2\).

### Step-by-Step Solution:

1. **Identify the Oxidation States**:
- Let’s assume \(X\) is the lower oxidation state and \(Y\) is the higher oxidation state. Therefore, \(Y = X + 2\).

2. **Determine the Nature of Compounds**:
- For transition metals, compounds in lower oxidation states (like \(X\)) tend to form ionic compounds. This is because lower oxidation states usually have a larger ionic radius and lower charge density, which favors ionic bonding.
- Conversely, compounds in higher oxidation states (like \(Y\)) tend to be covalent. Higher oxidation states have a smaller ionic radius and higher charge density, which leads to stronger interactions with the electron cloud of other atoms, resulting in covalent bonding.

3. **Conclusion on Ionic and Covalent Nature**:
- Thus, we can conclude:
- Compounds in oxidation state \(X\) (lower oxidation state) are ionic.
- Compounds in oxidation state \(Y\) (higher oxidation state) are covalent.

4. **Final Answer**:
- Based on the analysis, we can summarize the findings:
- If \(X < Y\), then compounds in oxidation state \(X\) are ionic, and compounds in oxidation state \(Y\) are covalent.