Answer:
A. 1:1
Explanation:
The ratio of metal cationic (+) atom to nonmetal anionic (-) atom in the sodium and bromine compound is 1:1 because sodium needs to lose one electron and bromine needs one electron to become stable and complete its outermost shell. When sodium lose electron, it become cation and gain +1 charge while on the other hand, the bromine accept one electron and become anion and gain -1 charge so that's why we can say that there is 1:1 of metal cationic (+) atom to nonmetal anionic (-) atom in the sodium and bromine compound.