S>Al>Na>KReason:-Electronegativity increases as the electrons in valence shell increases. Also it decreases from moving top to bottom in a group and left to right across a period.Sulphur having 6 electrons in valence shell is the highest electronegative element here while potassium having 1 electron in valence shell is the least .

Arranging Elements According to Electronegativity:

Electronegativity is defined as the ability of an atom to attract the shared pair of electrons towards itself in a covalent bond. The electronegativity of an element depends on several factors such as the number of valence electrons, atomic size, and nuclear charge. Based on the electronic configuration, the following is the arrangement of the elements in increasing order of electronegativity:

1. Na (2,8,1):
- Sodium has one valence electron, which is loosely held by the atom.
- It has a relatively large atomic size and low nuclear charge, which makes it less electronegative than other elements.
- Therefore, it has the lowest electronegativity among the given elements.

2. K (2,8,8,1):
- Potassium has one valence electron, which is also loosely held by the atom.
- However, it has a slightly larger atomic size than sodium and a higher nuclear charge, which makes it slightly more electronegative than sodium.
- Therefore, it has a higher electronegativity than sodium but lower than the other two elements.

3. Al (2,8,3):
- Aluminium has three valence electrons, which are held more tightly by the atom due to the lower atomic size and higher nuclear charge compared to sodium and potassium.
- Therefore, it has a higher electronegativity than both sodium and potassium but lower than sulfur.

4. S (2,8,6):
- Sulfur has six valence electrons, which are held even more tightly by the atom due to the smaller atomic size and higher nuclear charge compared to all the other elements.
- Therefore, it has the highest electronegativity among the given elements.

Conclusion:

- Based on the electronic configuration, the elements can be arranged in the increasing order of electronegativity as follows: Na < k="" />< al="" />< />
- Electronegativity increases from left to right across a period and decreases down a group in the periodic table.
- The four elements given in the question belong to different groups in the periodic table, which explains why the arrangement of their electronegativity is not strictly in accordance with the periodic trend.