select the correct answer\nwhich pair of elements can form ionic bonds?\na. copper (cu) and nitrogen (n)\nb…

Explanation:

Step1: Recall ionic - bond formation condition

Ionic bonds form between a metal and a non - metal with a large electronegativity difference (usually > 1.7).

Step2: Analyze option A

Copper (Cu) is a metal with electronegativity around 1.90, nitrogen (N) has an electronegativity of about 3.04. The electronegativity difference $\Delta\chi=3.04 - 1.90 = 1.14<1.7$.

Step3: Analyze option B

Gallium (Ga) is a metal with electronegativity around 1.81, phosphorus (P) has an electronegativity of about 2.19. The electronegativity difference $\Delta\chi=2.19 - 1.81 = 0.38<1.7$.

Step4: Analyze option C

Hydrogen (H) has an electronegativity of 2.20, sulfur (S) has an electronegativity of about 2.58. The electronegativity difference $\Delta\chi=2.58 - 2.20 = 0.38<1.7$.

Step5: Analyze option D

Phosphorus (P) has an electronegativity of 2.19, fluorine (F) has an electronegativity of 3.98. The electronegativity difference $\Delta\chi=3.98 - 2.19 = 1.79>1.7$, but both are non - metals.

Step6: Analyze option E

Potassium (K) is a metal with electronegativity 0.82, bromine (Br) is a non - metal with electronegativity 2.96. The electronegativity difference $\Delta\chi=2.96 - 0.82 = 2.14>1.7$.

Answer:

E. potassium (K) and bromine (Br)