Answer:
The mass of NaBr needed is 0.22969 g.
Explanation:
1 mole of NaBr contains 22.4 dm^3 of NaBr
Therefore, 0.05 dm^3 (50/1000 = 0.05 dm^3) of NaBr = 0.05/22.4 = 0.00223 mol of NaBr
MW of NaBr = 23 + 80 = 103 g/mol
Mass of NaBr = number of moles × MW = 0.00223 × 103 = 0.22969 g