SAT Question of the Day

If you burn Na in air, the following reactions take place:
Na + O2 => A
A + O2 => B
Note: A and B are two different substances and the chemical equations are NOT balanced.

What it is the mass percentage of oxygen in substance "A"?

(A) 25.8 %
(B) 41 %
(C) 74.2 %
(D) 59 %
(E) None of the above.