The ionisation energy and electron affinity of an element are 13.0 eV and 3.8 eV respectively. The numerical value of its electronegativity is

On Mulliken scale, E . N .=$\frac{\mathrm{I}.\mathrm{E}+\mathrm{E}·\mathrm{A}}{2}=\frac{13+3.8}{2}=8.4$

The Mulliken EN value of an element is 2.8 times greater than Pauling’s EN value. Using this relation and simplifying the calculated value, we have:

So, on Pauling scale = $\frac{8.4}{2.8}=3$