Which is the formula mass of na2so4

142.04 g/mol

That is it

Explanation:

Formula mass of a compound is calculated by taking the sum of atomic masses of all the elements present in the compound.

Since, atomic mass of Na = 23 g/mol

Atomic mass of S = 32 g/mol

Atomic mass of O = 16 g/mol

Hence, formula mass of will be as follows.

                  Formula mass =

                                           = 142 g/mol

Thus, we can conclude that formula mass of is 142 g/mol.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)