Question

Calculate the mass of a formula unit of the complex $FeS{O}_4.7H_{2}O$ in unified atomic mass unit.

• A. 230 u
• B. 250 u
• C. 278 u
• D. 270 u

Answer 1

The correct option is C 278 u

The atomic mass of iron ($Fe$) = 56 u, sulphur ($S$) = 32 u,
Oxygen ($O$) = 16 u, hydrogen ($H$) = 1 u

So, the molecular mass of the complex $FeS{O}_4.7H_{2}O$
$=(56+32+11\times 16+14\times 1)$ = 278 u