Which element has the lowest electronegativity?

Given below are two statements:
Statement $I$: The correct order of electronegativity of fluorine, oxygen and nitrogen is $F > O > N$.
Statement $II$: The oxidation state of oxygen in $OF_2$ is $+2$ and in $Na_2O$ is $-2$.

Let electronegativity,ionisation energy and electron affinity be represented as $EN$,$IP$ and $EA$ respectively. Which one of the following equations is correct according to Mulliken?

On going from right to left in a period in the periodic table,the electronegativity of the elements:

Which of these has no unit?

The electronegativity of $C$,$H$,$O$,$N$ and $S$ are $2.5$,$2.1$,$3.5$,$3.0$ and $2.5$ respectively. Which of the following bonds is most polar?