Answer:
All atoms heavier than barium
Explanation:
In the periodic table, elements are divided into blocks. We have the;
s- block elements
p- block elements
d- block elements
f- block elements
However, immediately after Barium, we now encounter elements that have f-orbitals. Barium possesses a fully filled d-orbital. Hence after it, we see elements with 4f and 5f orbitals called the Lanthanides and actinides. The elements following the lanthanide and actinide series possess completely filled f-orbitals as inner orbitals.
Hence elements heavier than barium all possess f-orbitals.
Ionic bonds is formed between metal and nonmetal with opposite charges. Metal have (+) charge and nonmetals often have (-) charge.
Choice (a) is wrong because both charges are the same.
Choice (c) is wrong b/c same changes.
Si and O do not have charges for now. (d) is wrong.
Choice (b) is correct. Opposite charges and the ionic compound is BaCl2
I think it may be A.
But I'm not sure
It's a because if you add them together you till get 1.40
