# Environmental Science: Numerical Questions – Energy (Nuclear Fission)

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## Nuclear Fission

Q 1 A typical fission reaction involving an atom of92U235 leads to a mass defect kg. How much energy is going to be released by 1.0 g of92U235?

(1) 3.33 × 10 − 11 MJ

(2) 2.23 × 1012 MJ

(3) 2.56 × 104 MJ

(4) 8.53 × 104 MJ

Answer: Option (4) 8.53 × 104 MJ

Mass Defect = 0.37 × 10 − 27 kg

Amount of92U235 = 1 gm

E = mc2

Number of Atoms in 5 gm of92U235 = nA

=

=

=

Total Energy = Energy of 1 atom Number of Atoms

Q 2 In a nuclear fission reaction involving 235U92 and a slow neutron, the mass defect is found to be 0.223 U. How much energy will be released from 5.0 gram of 235U92?

(1) 426.7 GJ

(2) 85.3 GJ

(3) 170.6 GJ

(4) 42.6 GJ

Answer: Option (1) 426.7 GJ

Mass Defect = 0.223 u

Amount of92U235 = 5 gm

Mass Defect

E = mc2

Total Energy Released from 5 gm of 92U = nA mc2

n = number of moles

A = Avogadro՚s number

= 437.19 GJ

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