The correct order of decreasing electronegativity values among the element I-beryllium, II-oxygen, III-nitrogen and IV-magnesium is

Options

A. `II gt III gt I gt IV`
B. `III gt IV gt II gt I`
C. `I gt I gt III gt IV`
D. `I gt Iigt IV gt III`

Answer

To determine the correct order of decreasing electronegativity values among the elements beryllium (Be), oxygen (O), nitrogen (N), and magnesium (Mg), we can follow these steps:

### Step-by-Step Solution:

1. **Understand Electronegativity**:
- Electronegativity is the tendency of an atom to attract shared electrons in a chemical bond. The higher the electronegativity, the stronger the atom's ability to attract electrons.

2. **Identify the Elements**:
- The elements in question are:
- I. Beryllium (Be)
- II. Oxygen (O)
- III. Nitrogen (N)
- IV. Magnesium (Mg)

3. **Locate the Elements on the Periodic Table**:
- Beryllium (Be) and Magnesium (Mg) are in Group 2 (alkaline earth metals).
- Oxygen (O) and Nitrogen (N) are in Group 16 and Group 15 respectively (nonmetals).

4. **Analyze the Trends in Electronegativity**:
- Electronegativity generally increases across a period (from left to right) and decreases down a group (from top to bottom).
- In the second period, nitrogen (N) and oxygen (O) have higher electronegativities than beryllium (Be) and magnesium (Mg) due to their smaller atomic size and greater effective nuclear charge.

5. **Rank the Electronegativity Values**:
- From the periodic trends:
- Oxygen (O) has the highest electronegativity.
- Nitrogen (N) is next.
- Beryllium (Be) follows.
- Magnesium (Mg) has the lowest electronegativity.

6. **Write the Final Order**:
- The correct order of decreasing electronegativity is:
- II. Oxygen (O) > III. Nitrogen (N) > I. Beryllium (Be) > IV. Magnesium (Mg)

### Final Answer:
The correct order of decreasing electronegativity values among the elements is:
**Oxygen (O) > Nitrogen (N) > Beryllium (Be) > Magnesium (Mg)**