Explanation:
Given that,
(a) Speed, 
Mass of the electron, 
Mass of the proton, 
The wavelength of the electron is given by :



The wavelength of the proton is given by :



(b) Kinetic energy, 
The relation between the kinetic energy and the wavelength is given by :






Hence, this is the required solution.
<h2>Answer: Francium
</h2>
Let's start by explaining that electronegativity is a term coined by Linus Pauling and is determined by the <em>ability of an atom of a certain element to attract electrons when chemically combined with another atom.
</em>
So, the more electronegative an element is, the more electrons it will attract.
It should be noted that this value can not be measured directly by experiments, but it can be determined indirectly by means of calculations from other atomic or molecular properties of the element. That is why the scale created by Pauling is an arbitrary scale, where the maximum value of electronegativity is 4, assigned to Fluorine (F) and the <u>lowest is 0.7, assigned to Francium (Fr).</u>
S= 343m/s
F=256Hz
WL= 343ms/256-1
WL=V/F
= 1.339844m