What's the answer to the question in the image attached?

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8