Question

Formula to find electronegativity of elements

Answer 1

Electronegativity cannot be directly measured and must be calculated from other atomic or molecular properties.
The most commonly used method of calculation is that originally proposed by Linus Pauling. This gives a dimentionless quantity commonly referred to as the Pauling scale (χ_r), on a relative scale running from around 0.7 to 3.98.

The methods of calculation are highly complicated and your current knowledge in physics and chemistry will be insufficient to understand them.