Nuclear Physics | Physics JEE previous year questions with Solutions

Q 1 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct? [2024]

${}_{56}^{144}B a + {}_{36}^{89}K r + 3 {}_{0}^{1}n$
${}_{56}^{144}B a + {}_{36}^{89}K r + 4 {}_{0}^{1}n$
${}_{51}^{153}S b + {}_{41}^{99}N b + 3 {}_{0}^{1}n$
${}_{56}^{140}X e + {}_{38}^{94}S r + 3 {}_{0}^{1}n$

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(1)

After balancing mass number and atomic number,the original fission reaction is given by,

${}_{92}^{235}U + {}_{0}^{1}n \to {}_{56}^{144}B a + {}_{36}^{89}K r + 3 {}_{0}^{1}n$

Q 2 :

In a hypothetical fission reaction

${}_{92}{X^{236}} \to {}_{56}{Y^{141}} + {}_{36}{Z^{92}} + 3 R$

The identity of emitted particles (R) is [2024]

$γ - r a d i a t i o n s$
$E l e c t r o n$
$N e u t r o n$
$P r o t o n$

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(3)

Z in LHS = 92

Z in RHS = 56 + 36 = 92

A in LHS = 236

A in RHS = 141 + 92 = 233

Q 3 :

The energy released in the fusion of 2 kg of hydrogen deep in the sun is $E_{H}$ and the energy released in the fission of 2 kg of ${}^{235}U$ is $E_{U}$ . The ratio $\frac{E_{H}}{E_{U}}$ is approximately

(Consider the fusion reaction as $4 {}_{1}^{1}H + 2 e^{-} \to {}_{2}^{4}H e + 2 v + 6 γ + 26.7$ MeV, energy released in the fission reaction of ${}^{235}U$ is 200 MeV per fission nucleus and $N_{A} = 6.023 \times 10^{23}$ ) [2024]

9.13
15.04
7.62
25.6

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(3)

In each fusion reaction, $4 {}_{1}^{1}H$ nucleus is used.

Energy released per Nuclei of ${}_{1}^{1}H = \frac{26.7}{4}$ MeV

$∴$ Energy released by 2 kg hydrogen,

$E_{H} = \frac{2000}{1} \times N_{A} \times \frac{26.7}{4} MeV$

$∴$ Energy released by 2 Kg Uranium,

$E_{U} = \frac{2000}{235} \times N_{A} \times 200 MeV$

$So, \frac{E_{H}}{E_{U}} = 235 \times \frac{26.7}{4 \times 200} = 7.84$

$∴$ Approximately close to 7.62

Q 4 :

The explosive in a Hydrogen bomb is a mixture of ${}_{1}{H^{2}, {}_{1}H^{3}}$ and ${}_{3}{L i^{6}}$ in some condensed form. The chain reaction is given by

${}_{3}{L i^{6} + {}_{0}{n^{1}}} \to {}_{2}{H e^{4} + {}_{1}{H^{3}}}$

${}_{1}{H^{2} + {}_{1}H^{3} \to {}_{2}{H e^{4} + {}_{0}{n^{1}}}}$

During the explosion the energy released is approximately [Given : M(Li) = 6.01690 amu, M ( ${}_{1}{H^{2}}$ ) = 2.01471 amu, M( ${}_{2}{H e^{4}}$ ) = 4.00388 amu, and 1 amu = 931.5 MeV] [2024]

28.12 MeV
12.64 MeV
16.48 MeV
22.22 MeV

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(4)

${}_{3}{L i^{6}} + {}_{0}{n^{1}} \to {}_{2}{H e^{4}} + {}_{1}{H^{3}}$

${}_{1}{H^{2}} + {}_{1}{H^{3}} \to {}_{2}{H e^{4}} + {}_{0}{n^{1}}$

${}_{3}{L i^{6}} + {}_{1}{H^{2}} \to 2 ({}_{2}{H e^{4})}$

$Q = Δ m c^{2}$

$Q = [M (L i) + M (H_{1}^{2}) - 2 \times M (H e^{4})] \times 931.5 M e V$

$Q = [6.01690 + 2.01471 - 2 \times 4.00388] \times 931.5 M e V$

$\Rightarrow Q \approx 22.22 M e V$

Q 5 :

The disintegration energy Q for the nuclear fission of ${}^{235}U \to {}^{140}C e + {}^{94}Z r + n$ is _________ MeV.

Given atomic masses of ${}^{235}U : 235.0439 u; C e : 139.905 u {}^{94}Z r : 93.9063 u; n : 1.0086 u,$ Value of $c^{2} = 931 M e V .$ [2024]

(208) ${}^{235}U \to {}^{140}C e + {}^{94}Z r + n$

Disintegration energy $Q = Δ m c^{2}$

$Q = (m_{R} - m_{P}) \cdot c^{2}$

$m_{R} = 235.0439 u$

$m_{P} = 139.9054 u + 93.9063 u + 1.0086 u = 234.8203 u$

$Q = (235.0439 u - 234.8203 u) c^{2} = 0.2236 \times 931 MeV$

$\approx 208.17 MeV \approx 208 MeV$

Q 6 :

Choose the correct nuclear process from the below options

$[p : proton, n : neutron, e^{-} : electron, e^{+} : positron, ν : neutrino, \bar{ν} : antineutrino]$ [2025]

$n \to p + e^{-} + \bar{ν}$
$n \to p + e^{-} + ν$
$n \to p + e^{+} + \bar{ν}$
$n \to p + e^{+} + ν$

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(1)

In nuclear processes, charge must be conserved. Also, a release of an electron $(e^{-})$ is always accompanied by a release of an antineutrino $(\bar{ν})$ .

$Hence, n \to p + e^{-} + \bar{ν} is the correct answer.$

Q 7 :

Match the List I with List II [2025]

List I List II

(A) ${}_{0}^{1}n +_{92}^{235} U \to_{54}^{140} Xe +_{38}^{94} Sr + 2_{0}^{1} n$ (I) Chemical reaction

(B) $2 H_{2} + O_{2} \to 2 H_{2} O$ (II) Fusion with +ve Q value

(C) ${}_{1}^{2}H +_{1}^{2} H \to_{2}^{3} He +_{0}^{1} n$ (III) Fission

(D) ${}_{1}^{1}H +_{1}^{3} H \to_{1}^{2} H +_{1}^{2} H$ (IV) Fusion with −ve Q value

Choose the correct answer from the options given below:

A–II, B–I, C–III, D–IV
A–III, B–I, C–II, D–IV
A–II, B–I, C–IV, D–III
A–III, B–I, C–IV, D–II

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(2)

(A) is fission reaction

(B) is a chemical reaction

(C) deuteron + deuteron → helium is exothermic process

(D) $H + {}^{3}H \to 2$ deuterons is endothermic process

Q 8 :

The energy released per fission of nucleus of ${}^{240}X$ is 200 MeV. The energy released if all the atoms in 120 g of pure ${}^{240}X$ undergo fission is ________ $\times 10^{25} MeV$ .

(Given $N_{A} = 6 \times 10^{23}$ ) [2023]

(6)

Q 9 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct.

${}_{56}^{144}{Ba} + {}_{36}^{89}{Kr} + 4 {}_{0}^{1}n$
${}_{56}^{140}{Xe} + {}_{38}^{94}{Sr} + 3 {}_{0}^{1}n$
${}_{51}^{153}{Sb} + {}_{41}^{99}{Nb} + 3 {}_{0}^{1}n$
${}_{56}^{144}{Ba} + {}_{36}^{89}{Kr} + 3 {}_{0}^{1}n$

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(4)

$Nuclear fission between neutron ({}_{0}^{1}n) and uranium isotope {}_{92}^{235}U$

${}_{92}^{235}U + {}_{0}^{1}n \to {}_{56}^{144}B a + {}_{36}^{89}K r + 3 {}_{0}^{1}n$

Q 10 :

The energy released when $\frac{7}{17.13}$ kg of ${}_{3}^{7}{Li}$ is converted into ${}_{2}^{4}{He}$ by proton bombardment is $α \times 10^{32} eV$ . The value of $α$ is ______. (Nearest integer)

(Mass of ${}_{3}^{7}{Li} = 7.0183$ u, mass of ${}_{2}^{4}{He} = 4.004$ u, mass of proton = 1.008 u and 1 u = 931 $MeV / c^{2}$ and Avogadro number $= 6.0 \times 10^{23}$ ) [2026]

(6)

${}_{3}^{7}L i + {}_{1}^{1}H ⇌ 2 ({}_{2}^{4}H e) + Q$

$Mass of Reactants:$

$M_{L i} + M_{p} = 7.0183 u + 1.008 = 8.0263 u$

$Mass of Product: 2 \times M_{H e} = 2 \times 4.004 u = 8.008 u$

$Mass defect (Δ m) = 8.0263 u - 8.008 u = 0.0183 u$

$Energy (Q) = Δ m c^{2} = 0.0183 \times 931 MeV \approx 17.0373 MeV$

$Number of Li atoms: N = \frac{Mass}{Molar mass} \times N_{A}$

$N = \frac{\frac{7}{17.13} kg}{7 \times 10^{- 3} kg / mol} \times 6.02 \times 10^{23} = \frac{6}{17.13} \times 10^{26}$

$E_{total} = N \times Q$

$E_{total} = 17.0373 \times \frac{1}{17.13} \times 6 \times 10^{26} \times 10^{6} eV$

$E_{total} \approx 6 \times 10^{32} eV$

$Comparing we get α = 6$

Topic Question Set

Q 1 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct? [2024]

Q 2 :

In a hypothetical fission reaction

${}_{92}{X^{236}} \to {}_{56}{Y^{141}} + {}_{36}{Z^{92}} + 3 R$

The identity of emitted particles (R) is [2024]

Q 5 :

The disintegration energy Q for the nuclear fission of ${}^{235}U \to {}^{140}C e + {}^{94}Z r + n$ is _________ MeV.

Given atomic masses of ${}^{235}U : 235.0439 u; C e : 139.905 u {}^{94}Z r : 93.9063 u; n : 1.0086 u,$ Value of $c^{2} = 931 M e V .$ [2024]

Q 6 :

Choose the correct nuclear process from the below options

$[p : proton, n : neutron, e^{-} : electron, e^{+} : positron, ν : neutrino, \bar{ν} : antineutrino]$ [2025]

Q 8 :

The energy released per fission of nucleus of ${}^{240}X$ is 200 MeV. The energy released if all the atoms in 120 g of pure ${}^{240}X$ undergo fission is ________ $\times 10^{25} MeV$ .

(Given $N_{A} = 6 \times 10^{23}$ ) [2023]

(6)

Q 9 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct.

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	List I		List II
(A)	${}_{0}^{1}n +_{92}^{235} U \to_{54}^{140} Xe +_{38}^{94} Sr + 2_{0}^{1} n$	(I)	Chemical reaction
(B)	$2 H_{2} + O_{2} \to 2 H_{2} O$	(II)	Fusion with +ve Q value
(C)	${}_{1}^{2}H +_{1}^{2} H \to_{2}^{3} He +_{0}^{1} n$	(III)	Fission
(D)	${}_{1}^{1}H +_{1}^{3} H \to_{1}^{2} H +_{1}^{2} H$	(IV)	Fusion with −ve Q value

Topic Question Set

Q 1 : Which of the following nuclear fragments corresponding to nuclear fission between neutron (n01) and uranium isotope (U92235) is correct? [2024]

Q 2 : In a hypothetical fission reaction X23692→Y14156+Z9236+3R The identity of emitted particles (R) is [2024]

Q 5 : The disintegration energy Q for the nuclear fission of U235→C140e+Z94r+n is _________ MeV. Given atomic masses of U235:235.0439 u; Ce:139.905 u Z94r:93.9063 u; n:1.0086 u, Value of c2=931 MeV. [2024]

Q 6 : Choose the correct nuclear process from the below options [p:proton, n:neutron, e-:electron, e+:positron, ν:neutrino, ν¯:antineutrino] [2025]

Q 8 : The energy released per fission of nucleus of X240 is 200 MeV. The energy released if all the atoms in 120 g of pure X240 undergo fission is ________ ×1025 MeV. (Given NA=6×1023) [2023]

(6)

Q 9 : Which of the following nuclear fragments corresponding to nuclear fission between neutron (n01) and uranium isotope (U92235) is correct.

Q 10 : The energy released when 717.13kg of Li37 is converted into He24 by proton bombardment is α×1032 eV. The value of α is ______. (Nearest integer) (Mass of Li37=7.0183 u, mass of He24=4.004 u, mass of proton = 1.008 u and 1 u = 931 MeV/c2 and Avogadro number =6.0×1023) [2026]

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Q 1 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct? [2024]

Q 2 :

In a hypothetical fission reaction

${}_{92}{X^{236}} \to {}_{56}{Y^{141}} + {}_{36}{Z^{92}} + 3 R$

The identity of emitted particles (R) is [2024]

Q 5 :

The disintegration energy Q for the nuclear fission of ${}^{235}U \to {}^{140}C e + {}^{94}Z r + n$ is _________ MeV.

Given atomic masses of ${}^{235}U : 235.0439 u; C e : 139.905 u {}^{94}Z r : 93.9063 u; n : 1.0086 u,$ Value of $c^{2} = 931 M e V .$ [2024]

Q 6 :

Choose the correct nuclear process from the below options

$[p : proton, n : neutron, e^{-} : electron, e^{+} : positron, ν : neutrino, \bar{ν} : antineutrino]$ [2025]

Q 8 :

The energy released per fission of nucleus of ${}^{240}X$ is 200 MeV. The energy released if all the atoms in 120 g of pure ${}^{240}X$ undergo fission is ________ $\times 10^{25} MeV$ .

(Given $N_{A} = 6 \times 10^{23}$ ) [2023]

Q 9 :

Which of the following nuclear fragments corresponding to nuclear fission between neutron $({}_{0}^{1}n)$ and uranium isotope $({}_{92}^{235}U)$ is correct.