Answer:
Nitrogen
Explanation:
Nitrogen has 5 Valence Electrons.
And its atomic mass is also less than Bismuth.
There are other elements in the 5th row but this one has the lowest atomic mass compared to the others.
Can you please explain what the BTB is so I may help ya?
Answer:
it is a pathways by which a chemical substance moves thru biotic and abiotic components of earth. example is the water cycle