Molar mass :
NH₃ = 17.0 g/mol
(NH₄)₂SO₄ = 132 g/mol
2 NH₃ + H₂SO₄ = (NH₄)₂SO₄
2 x 17 g NH₃ ------------ 132 g (NH₄)₂SO₄
( mass NH₃) ------------ 1.90 x 10⁵ (NH₄)₂SO₄
( mass NH₃) = (1.90 x 10⁵) x 2 x 17 / 132
( mass NH₃) = 6460000 / 132
( mass NH₃) = 48939.39 g
in kg :
48939.39 / 1000 = 48.93 kg = 4.893 x 10¹ kg
hope this helps!