The correct answer would be option 3. I order for a single displacement to occur there must be a single element and one compound. From then, the single element will then swap places with one of the elements in the compound (or in this case single circle and combined circles). Hope this helped!
Answer:
(BH3 follows the octet rule by dimerizing, as Hadi Kurniawan AR pointed out.) For H and He, an "octet" = 2 electrons. Boron does prefer to follow the octet rule, in that it likes to form borate compounds such as NaBH4. It also is happy to form compounds with elements with lone pairs.
Answer:
The number of protons in an atom define each individual element because the number of protons is the atomic number which is the defining property of an atom and never changes. The number of protons determines an atom's identity. For example, Oxygen has an atomic number of 8, so it has 8 protons, so no matter what ionic compound or molecule it's part of, every single Oxygen atom will always have 8 protons each.
It is actually Group 3A elements. I just took the test.
