Question

The energy liberated on complete fission of 1 kg of $92U^{235}$ is (Assume 200 MeV energy is liberated on fission of 1 nucleus).

• A. $8.2 \times 10^{10}J$
• B. $8.2 \times 10^{9}J$
• C. $8.2 \times 10^{13}J$
• D. $8.2 \times 10^{16}J$

Answer 1

Answer: (C)

$8.2 \times 10^{13}J$

Answer 2

Mass of a uranium nucleus

$= 92 \times 1.6725 \times 10^{- 27} + 143 \times 1.6747 \times 10^{- 27}$

$= 393.35 \times 10^{- 27}kg$

Number of nuclei in the given mass

$= \frac{1}{393.35 \times 10^{- 27}} = 2.542 \times 10^{24}$

Energy released $= 200 \times 2.542 \times 10^{24}MeV$

$= 5.08 \times 10^{26}MeV = 8.135 \times 10^{13}J = 8.2 \times 10^{13}J$