Answer:
0.409 mol
Explanation:
The formula to find he number of moles is:
No. of moles = [tex]\frac{mass}{Mr}[/tex]
Mr of MgBr₂ = 24.3 + (79.9 × 2) = 184.1
Mass = 75.25g
So, no. of moles = [tex]\frac{75.24}{184.1}[/tex]
No. of moles = 0.409 mol [to 3 significant figures]