Molar mass of P₂O₅ = 141.948 g/mol which is approximately 142 g/mol.
Explanation:
Molar mass of AlCl₃
Molar mass = 26.982 + 35.5 × 3 = 133.32 g/mol
Molar mass of BaCl₂
Molar mass = 137.33 + 35.5 × 2 = 208.33 g/mol
Molar mass of MgCl₂
Molar mass = 24.305 + 35.5×2 = 95.305 g/mol
Molar mass of P₂O₅
Molar mass = 30.974×2 + 16× 5 = 141.948 g/mol