Molar mass is the mass of 1 mole of substance
Molar mass of a compound is the sum of the products of the atomic masses of the elements by the number of atoms of each element
we can use the following equation
molar mass of (NH₄)₂SO₄ = 2 (atomic mass of N + 4(atomic mass of H)) + atomic mass of S + 4(atomic mass of O)
atomic masses of the elements are as follows
N - 14.01
H - 1.01
S - 32.07
O - 16.00
substituting these values
molar mass of (NH₄)₂SO₄ = 2 (14.01 + 4(1.01) + 32.07 + 4(16.00)
molar mass of (NH₄)₂SO₄ = 2 (14.01 + 4.04) + 32.07 + 64.00 = 2 (18.05) + 32.07 + 64.00
molar mass of (NH₄)₂SO₄ = 36.1 + 32.07 + 64.00 = 132.17
molar mass of (NH₄)₂SO₄ is 132.17 g/mol