Mass defect for the isotope thorium-234 = 1.85864 amuHow many kilograms does the mass defect represent?

Use the conversion 1 amu = 1.66054 × 10⁻²⁷ kg. The mass defect is 1.85864 amu × 1.66054 × 10⁻²⁷ kg/amu ≈ 3.09 × 10⁻²⁷ kg, so the correct choice is 3.09 × 10⁻²⁷ kg.

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