The molar mass of barium nitrate (Ba(NO3)2) is 261.35 g/mol. What is the mass of 5.30 × 1022 formula units of Ba(NO3)2?

First convert formula units to moles using Avogadro’s number: (5.30 × 10²²) ÷ (6.022 × 10²³) = 0.0880 mol Ba(NO₃)₂. Then multiply by the molar mass: 0.0880 mol × 261.35 g/mol = 23.0 g. The mass is 23.0 g, choice C.

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