Question

Mass defect in a fusion reaction is 0.36%. Energy liberated when 1 gm of material undergoes fusion in kWh is

• A. 36000
• B. 9000
• C. 90000
• D. 3600

Answer 1

Answer: (C)

90000

Answer 2

Mass defect, $\Delta m = 0.36 \%$ of 1 gm \hspace30mm = \frac{0.36}{100}g = 0.36 \times10^{-5} kg Energy liberated $= \Delta mc^{2}$ \hspace30mm = 0.36 \times 10^{-5}\times \left(3\times 10^{8}\right)^{2} J \hspace30mm = \frac{0.36 \times 10^{-5} \times 9\times 10^{16}}{3.6\times 10^{6}} kW h \hspace30mm \left( 1kWh = 3.6 \times 10^{6} J\right) \hspace30mm = 90000 kW h