Answer:
261.3404 u
Step-by-step explanation:
The symbol for barium nitrate is
Ba (NO3)2
Therefore there is
1 barium atom
2 nitrogen atoms
6 oxygen atoms
Add the molar mass of these atoms together to get the molar mass of barium nitrate
137.327 +(14.0067×2) +(16 ×6)
=261.3404 u