I think it's M.B is the second letter, C is the third, D is the 4th. The difference between these letters is one. D-G is 3 and G-J is 3 so I'd assume that the next letter is the third after J which is M.2-3-4-7-10-13
g.
3CO(g) + Fe2O3(s) Fe(s) + 3CO2(g)
Something having g to do with the letter Z
If G + 5 = g - 2 then G = g + 3 and g = G - 3
A
k
d
i
I,V
d
what is the next sequence a, d, g, j
G
O
k comes next, and then l.
It's K!
U (fourth, third, fourth, third, etc).