Answer:
The middle, or the transitional metals
Explanation:
When naming elements, we use roman numerals to indicate what their charge is. The charge of an element is affected by their number of valence electrons (outermost electrons).
Transitional metals are generally <u>multivalent</u>, meaning that element has more than one possible number of valence electrons. This makes them have more than one possible charge. Roman numerals indicate which charge of that element is used/discussed.
Answer is D 2 elements and a total of 3 atoms
Answer:
Coefficient in front of the 
in the balanced equation - 1
Explanation:
The unbalanced Chemical equation is shown below as:-
On the left hand side,
There are 1 boron atom and 3 fluorine atoms and 1 sodium and hydrogen atoms.
On the right hand side,
There are 2 boron atoms and 6 hydrogen atoms and 1 sodium and fluorine atoms.
Thus,
leftside, 
must be multiplied by 2 to balance boron and right side, 
must be multiplied by 6 to balance fluorine. Left side, 
must be multiplied by 6 to balance sodium and hydrogen atoms.
Thus, the balanced reaction is:-
<u>Coefficient in front of the in the balanced equation - 1</u>
