Explanation:
It is known that electronegativity is the ability of an atom to attract electrons towards itself in order to attain stability. Generally, non-metals are electronegative in nature.
When we move from left to right in a periodic table then there will occur an increase in the electronegativity of the atoms.
Lithium (Li) is an alkali metal and it is highly electropositive in nature.
Barium (Ba) is an alkaline earth metal and it is also electropositive in nature. Also, it is placed gown in group 2 so it will readily lose electrons in order to gain stability.
Oxygen (O) is a group 16 element and it is a non-metal which is electronegative in nature.
Thus, we can conclude that order of increasing electronegativity for the given elements is as follows.
Ba < Li < O
