According to the law of conservation of mass, the amount of BARIUM present of the reactants is the same as the amount present in the products (the precipitate).
(11.21 g BaSO4) / (233.4 g/mol BaSO4) = 0.0480 mol BaSO4 and original barium salt
(10.0 g) / (0.0480 mol) = 208.3 g/mol
So it must have been BaCl2, because the molar mass of Barium is 137 which leave 71 grams left. Since Barium is a +2 charge, it means the atom next to it must be twice. Chlorine mass is 35, which twice is 71
Answer: 
Explanation: 1 gram is equal to 1000 Milligrams so

Since you go straight across its just multiplication so 0.00200x1000=200mg
To answer it in scientific notation it should just be
mg
Answer:
[O₂(g)] = 0.0037M
Explanation:
2SO₂(g) + O₂(g) => 2SO₃(g)
Conc: [SO₂(g)] [O₂(g)] [SO₃(g)] and [SO₂(g)] = [SO₃(g)]
Kc = [SO₃(g)]²/[O₂(g)][SO₂(g)]² => Kc = 1/[O₂(g)] = 270 if [SO₂(g)] = [SO₃(g)]
∴ [O₂(g)] = (1/270)M = 0.0037M
20 cups of flour, 30 eggs, and 10 cups of sugar