The energy equivalent of 0.5 g of a substance is:

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Accepted Answer

1.  **Formula:** Einstein's mass-energy equivalence relation is given by:
    $$ E = mc^2 $$
    where $E$ is energy, $m$ is mass, and $c$ is the speed of light in vacuum ($3 	imes 10^8 	ext{ m/s}$).
2.  **Unit Conversion:** The mass must be in SI units (kilograms). Given mass $m = 0.5 	ext{ g}$.
    $$ m = 0.5 	imes 10^{-3} 	ext{ kg} = 5 	imes 10^{-4} 	ext{ kg} $$
3.  **Calculation:** Substitute the values into the formula:
    $$ E = (0.5 	imes 10^{-3} 	ext{ kg}) 	imes (3 	imes 10^8 	ext{ m/s})^2 $$
    $$ E = (0.5 	imes 10^{-3}) 	imes (9 	imes 10^{16}) $$
    $$ E = 4.5 	imes 10^{13} 	ext{ J} $$
4.  **Conclusion:** The energy equivalent is $4.5 	imes 10^{13}$ Joules.

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