Step-by-step explanation:
To convert from grams to moles we have to use the molar mass. Let's find the molar mass of AuBr.
molar mass of Au = 196.97 g/mol
molar mass of Br = 79.90 g/mol
molar mass of AuBr = 196.97 g/mol + 79.90 g/mol
molar mass of AuBr = 276.87 g/mol
Once we have the molar mass, we can find the number of moles of AuBr that are present in 400 g of it.
mass of AuBr = 400 g
moles of AuBr = 400 g/(276.87 g/mol)
moles of AuBr = 1.44 moles
Answer: 1.44 moles of AuBr are present in 400 g of it.