Chemistry help please calculating number of atoms in given grams of atom?

A.
Molar mass of H₂S = (1.0×2 + 32.1) g/mol = 34.1 g/mol
No. of moles of H₂S = (1.00 × 1000 g) / (34.1 g/mol) = 1000/34.1 mol

Avogadro constant = 6.022 × 10²³ /mol
No. of H₂S molecules = (1000/34.1 mol) × (6.022 × 10²³ /mol) = (6.022 × 10²⁶)/34.1

Each H₂S molecule contains 1 S atom.
No. of S atoms = [(6.022 × 10²⁶)/34.1] = 1.77 × 10²⁵


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B.
As in A, no. of H₂S molecules = (6.022 × 10²⁶)/34.1

Each H₂S molecule contains 2 H atoms.
No. of H atoms = [(6.022 × 10²⁶)/34.1] × 2 = 3.53 × 10²⁵


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C.
Each formula unit of K₂CO₃ contains 3 O atoms.
No. of formula units of K₂CO₃ = 1000000/3

Avogadro constant = 6.022 × 10²³ /mol
No. of moles of K₂CO₃ = (1000000/3) / (6.022 × 10²³ /mol) = 5.535 × 10⁻¹⁹ mol

Molar mass of K₂CO₃ = (39.0×2 + 12.0 + 16.0×3) g/mol = 138.0 g/mol
Mass of K₂CO₃ = (5.535 × 10⁻¹⁹ mol) × (138.0 g/mol) = 7.64 × 10⁻¹⁷ g