The starting materials in a nuclear change have a total mass of 2.3465 × 10–27 kg. After the change, the resulting materials have a mass of 2.3148 × 10–27 kg.How much energy was released during the change?

The mass converted to energy is the difference between the starting and resulting masses: (2.3465 − 2.3148) × 10⁻²⁷ kg = 3.17 × 10⁻²⁹ kg. Using Einstein’s equation E = mc² with c ≈ 3.00 × 10⁸ m/s gives E = (3.17 × 10⁻²⁹)(3.00 × 10⁸)² ≈ 2.85 × 10⁻¹² J. Therefore, the energy released is 2.85 × 10⁻¹² J, choice A.

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