Question

Which of the following pairs of elements will NOT form an ionic solid?
Question 3 options:

a)

calcium and sulphur

b)

strontium and iodine

c)

francium and fluorine

d)

rubidium and chlorine

e)

selenide and hydrogen

Answer 1

e) selenide and hydrogen.

Reason: ionic solids form from a metal cation and a nonmetal anion (electron transfer). Options a–d are metal + nonmetal pairs (e.g., CaS, SrI2, FrF, RbCl). "Selenide" is already an anion (Se2–); combining with hydrogen gives H2Se (a covalent molecular gas) rather than an ionic solid.