IIT-JEE 2007 · Paper 1 · Physics Q8

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PhysicsSingle correct+3 / -1Question 8 of 66

In the options given below, let $E$ denote the rest mass energy of a nucleus and $n$ a neutron. The correct option is

E(^{236}_{92}\mathrm U)>E(^{137}_{53}\mathrm I)+E(^{97}_{39}\mathrm Y)+2E(n)

E(^{236}_{92}\mathrm U)<E(^{137}_{53}\mathrm I)+E(^{97}_{39}\mathrm Y)+2E(n)

E(^{236}_{92}\mathrm U)<E(^{140}_{56}\mathrm{Ba})+E(^{94}_{36}\mathrm{Kr})+2E(n)

E(^{236}_{92}\mathrm U)=E(^{140}_{56}\mathrm{Ba})+E(^{94}_{36}\mathrm{Kr})+2E(n)

Answer and worked solution

Official answer: A

Fission releases energy. When a heavy nucleus such as $^{236}$ U splits into medium nuclei plus neutrons (nucleon number conserved: $137+97+2=236$ ), the products are more tightly bound, so their total rest energy is less than that of the uranium nucleus:
$E(^{236}\mathrm U)>E(^{137}\mathrm I)+E(^{97}\mathrm Y)+2E(n).$

(A)

Topics:Nuclear fission and fusion Mass defect and binding energy

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IIT-JEE 2007 · Paper 1, Physics question 8