Which of the following compounds contains 57.5% sodium by mass?

Question

*NaI
*NaOH
*NaHCO3
*NaSO3

Answer 1

You omitted a 2 on Na2SO3. There is no NaSO3.
%Na in NaI = (atomic mass Na/molar mass NaI)*100 = ?
Do them until you find a 57.5% for Na.

Answer 2

NaOH