Electronegativities of the elements Na, Al, P, and Cl follow a specific trend across the period. Based on this trend, an electron will be most strongly attracted to

Electronegativity increases across the period on a periodic table.

Explanation:

Electronegativity is the ability of an atom to attract electron to itself.

All elements on the periodic table combines in order to have a complete octet i. e they all want to be like the noble gases, group 0 elements.

This is what drives most atom to combine chemically. By so doing, they either lose or gain electrons.

Cl belongs to the 7th group on the periodic table. It is the second element in this halogen group. Most halogens are notable for their high electronegativity. They have 7 electrons in their outermost shell and would require just an electron to complete their octet.

This makes them highly reactive and combine readily with other elements.

The halogens have a strong attraction for valence electrons. The higher the electronegativity value, the stronger the attraction an atom has for valence electrons.

Most metals like Al and Na are electropositive and readily donates or lose electrons so as to have a complete octet.

The given elements Na, Al, P and Cl are all elements of period 3.

Atomic number of sodium is 11 with electronic distribution 2, 8, 1.

Atomic number of aluminium is 13 with electronic distribution 2, 8, 3.

Atomic number of phosphorous is 15 with electronic distribution 2, 8, 5.

Atomic number of chlorine is 17 with electronic distribution 2, 8, 7.

An element that has the tendency to readily attract an electron towards itself is known as an electronegative element.

So, out of the given elements chlorine is the most electronegative. Hence, an electron will be most strongly attracted to chlorine.