What mass of Na2SO4 is needed to make 2.5L of 2.0M solution? (Na=23g; S=32g; O=16g)

178g

284g

356g

710g

The molar mass of Na₂SO₄ -

2 x Na - 2 x23 = 46

1 x S - 1 x 32 = 32

4 x O - 4 x 16 = 64

total = 46 + 32 + 64 = 142 g/mol

the molarity of solution - 2.0 M

in 1 L of solution, 2.0 moles

Therefore in 2.5 L - 2 mol/L x 2.5 L = 5 mol

then the mass of Na₂SO₄ required = 142 g/mol x 5 mol = 710 g