What's the mr of 2MgSO4?

The Mr of 2MgSO4 is 240.6 g/mol

calculation

The atomic mass of 2MgSO4 = 2 (atomic mass of Mg + atomic mass of S + atomic mass of 4 atoms of O)

from periodic table the atomic mass of Mg = 24.3 g/mol, s=32 g/mol,

O = 16 g/mol

Atomic mass of 2MgSO4 is therefore = 2 [ 24.3 + 32 + (16 x4) ]

= 240.6 g/mol