The ionisation potential and electron affinity of an element "X" are 275 and 86 kcal/mole. Then the electronegativity of "X" according to Mulliken scale is

Options

A. 2.8
B. 0
C. 4
D. 2.6

Explanation

To find the electronegativity of element "X" according to the Mulliken scale, we can follow these steps:

### Step 1: Understand the Formula
The electronegativity (χ) according to the Mulliken scale is calculated using the formula:
\[ \chi = \frac{I + A}{2} \]
where:
- \(I\) = Ionization Potential (IP) in kcal/mole
- \(A\) = Electron Affinity (EA) in kcal/mole

### Step 2: Identify Given Values
From the question, we have:
- Ionization Potential (IP) = 275 kcal/mole
- Electron Affinity (EA) = 86 kcal/mole

### Step 3: Substitute Values into the Formula
Now, substitute the values of IP and EA into the formula:
\[ \chi = \frac{275 + 86}{2} \]

### Step 4: Calculate the Sum
Calculate the sum of the ionization potential and electron affinity:
\[ 275 + 86 = 361 \]

### Step 5: Divide by 2
Now, divide the sum by 2 to find the electronegativity:
\[ \chi = \frac{361}{2} = 180.5 \]

### Step 6: Final Calculation
However, the Mulliken scale typically uses a different divisor, which is 129 (as mentioned in the video transcript). Therefore, we should actually calculate:
\[ \chi = \frac{275 + 86}{129} \]
Calculating this gives:
\[ \chi = \frac{361}{129} \approx 2.8 \]

### Conclusion
Thus, the electronegativity of element "X" according to the Mulliken scale is approximately **2.8**.

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