Which of the following pairs of elements would most likely combine to form a salt? o and f i and f na and al k and i

             K and I

                      Salt is a neutral compound made up of a positive cation and a negative anion joint together via an ionic bond. Also, ionic bond is formed between metals and non metals. Furthermore, if the electronegativity difference between the metal and non metal is greater than 1.7 then it will go for ionic bonding. Let us calculate the electronegativity difference between the given pair of elements and predict the ionic bond between them.

1) F and O;

               E.N of Fluorine     =  4.00

               E.N of Oxygen      =  3.50

              Difference                 0.50                 (Not Ionic, No Salt Formation)

As both are non metals hence, the formation of ionic bond is not favored.

2) F and I;

               E.N of Fluorine        =  4.00

               E.N of Iodine           =  2.70

              Difference                     1.30               (Not Ionic, No Salt Formation)

Again, both elements are non metals with less electronegativity difference, therefore no salt formation takes place.

3) Na and Al;

               E.N of Aluminium     =  1.60

               E.N of Sodium          =  0.90

              Difference                      0.70           (Not Ionic, No Salt Formation)

Both are metals, hence ionic bond is not formed therefore, fails to form salt.

4) K and I;

               E.N of Iodine                =  2.70

               E.N of Potassium         =  0.80

              Difference                          1.90       (Ionic, Salt Formation favored)

Potassium is a metal and Iodine is non metal also, electronegativity difference is greater than 1.7 hence, electron transfer takes place and results in the formation of ions and salt.

true

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