Question

How much energy will be released when $10kg$ of $U^{235}$ is completely converted into energy ?

• A. $5\times {10}^{27}MeV$
• B. $5\times {10}^{24}MeV$
• C. $9\times {10}^{17}J$
• D. $Allofthese$

Answer 1

Answer: (C)

$9\times {10}^{17}J$

$10Kg$ means $10000gram$ so number of moles will be $10000/235=42.553$

So number of atoms $42.553\times 6.02\times {10}^{23}=256.169\times {10}^{23}atoms$

one atom weigh nearly $235amu$ and $1amu$ $get$ changed in energy $931.5Mev$

so total energy liberated $E=256.169\times 235\times 931.5\times {10}^{23}Mev=5.6\times {10}^{30}Mev=5.6\times {10}^{36}ev$

but $1ev=1.6\times {10}^{-19}Joule$ so energy becomes $5.6\times 1.6\times {10}^{17}Joule=8.96\times {10}^{17}Joule$

Option C is correct.