Which pair of elements will form an ionic bond? n and o k and br c and cl fe and ni

             K and Br

                      Ionic bond is formed between metals and non metals. Also, one of the easiest way to determine ionic bond between two atoms is to calculate the electronegativity difference between the two atoms. If the difference is greater than 1.7 then the bond will be ionic.

1) N and O;

               E.N of Oxygen     =  3.50

               E.N of Nitrogen    =  3.00

              Difference                 0.50                 (Not Ionic)

2) K and Br;

               E.N of Bromine       =  2.80

               E.N of Potassium    =  0.80

              Difference                     2.00                 (Ionic)

3) C and Cl;

               E.N of Chlorine     =  3.00

               E.N of Carbon       =  2.50

              Difference                   0.50                 (Not Ionic)

4) Fe and Ni;

               E.N of Nickle     =  1.90

               E.N of Iron         =  1.80

              Difference                 0.10                 (Not Ionic)

Hence it is proved that the greatest electronegativity difference is found between Potassium and Bromine (i.e. 2.0) which is greater than 1.7 therefore, they will form ionic bond.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong