Answer:
a. Tellurium
b. Rubidium
c. Argon
d. Astatine
Explanation:
a. An element of the same family as oxygen corresponds to group 16 or 6A, its most stable ion is -2, therefore if the ion has 54 electrons the neutral element should have 52 electrons and also 52 protons. Tellurium
b. The ions from alkali metals are +1, therefore the neutral elements have 1 more electron and proton, since the ion has 36 electrons the neutral element has 37. Rubidium
c. This is direct, look for the element with Z = 18. Argon
d. This is also direct, look for the element with Z = 85. Astatine