Question

When ${ }^{92} U _{235}$ undergoes fission $0.1 \%$ of its original mass is changed into energy. How much energy is released if $1 \,kg$ of ${ }^{92} U _{235}$ undergoes fission

• A. $9 \times 10^{10} \,J$
• B. $9 \times 10^{11}\, J$
• C. $9 \times 10^{12}\, J$
• D. $9 \times 10^{13}\, J$

Answer 1

Answer: (D)

$\Rightarrow \frac{0.1}{100} \times 1\, kg =\frac{1}{1000} \,kg =10^{-3} kg$
Using the equation
$E = mc ^{2} $
$=10^{-3} \times\left(3 \times 10^{8}\right)^{2} $
$=10^{-3} \times 9 \times 10^{16}$
$E =9 \times 10^{13} \,J$