Dual Nature, Atoms & Nuclei · JEE Main previous year questions

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2026 30 questions

Q432026 · 8 Apr 2026 · Shift 2
$K_{1}$ and $K_{2}$ be the maximum kinetic energies of photoelectrons emitted from a surface of a given material for the light of wavelength $λ_{1}$ and $λ_{2}$ , respectively. If $λ_{1} = 2 λ_{2}$ then the work function of material is given by :
1. A. $K_{2} + 2 K_{1}$
2. B. $2 K_{2} - K_{1}$
3. C. $K_{1} - 2 K_{2}$
4. D. $K_{2} - 2 K_{1}$
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Answer: D
Q442026 · 8 Apr 2026 · Shift 2
Two radioactive substances A and B of mass numbers 200 and 212 respectively, shows spontaneous $α$ -decay with same $Q$ value of $1 MeV$ . The ratio of energies of $α$ -rays produced by A and B is ____ .
1. A. $\frac{2548}{2650}$
2. B. $\frac{2706}{2646}$
3. C. $\frac{2597}{2600}$
4. D. $\frac{2862}{2499}$
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Answer: C
Q442026 · 6 Apr 2026 · Shift 1
The ratio of momentum of the photons of the $1^{st}$ and $2^{nd}$ line of Balmer series of Hydrogen atoms is $α / β$ . The possible values of $α$ and $β$ are:-
1. A.27 and 20
2. B.3 and 16
3. C.5 and 36
4. D.20 and 27
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Answer: D
Q412026 · 6 Apr 2026 · Shift 2
The energy released if hydrogen atoms are combined to form $_{2}^{4} He$ is ________ $MeV$ . (Take binding energies per nucleon of $_{1}^{2} H$ and $_{2}^{4} He$ as $1.1 MeV$ and $7.2 MeV$ , respectively)
1. A. $6.1$
2. B. $24.4$
3. C. $26.6$
4. D. $5$
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Answer: B
Q472026 · 6 Apr 2026 · Shift 2· Numerical answer
The de Broglie wavelength for an electron accelerated through the potential difference of $V_{1} volt$ is $λ_{1}$ . When the potential difference is changed to $V_{2} volt$ , the associated de Broglie wavelength is increased by $50%$ . If $(V_{1} / V_{2}) = (9/ α)$ , then the value of $α$ is ________.
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Answer: 4
Q362026 · 5 Apr 2026 · Shift 1
In the hydrogen atom, the electron makes a transition from the higher orbit ( $i$ ) to a lower orbit ( $f$ ). The ratio of the radius of the orbits in given by $r_{i} : r_{f} = 16 : 4$ . The wavelength of photon emitted due to this transition is ____ $nm$ . (Given Rydberg constant $= 1.0973 \times 1 0^{7} /m$ )
1. A.121
2. B.242
3. C.486
4. D.974
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Answer: C
Q412026 · 5 Apr 2026 · Shift 1
Light source having wavelength $331 nm$ is used to generate photo-electrons whose stopping potential is $0.2 V$ . The work function of the used metal in the experiment is $α \times 1 0^{- 19} J$ . The value of $α$ is ____. $(h = 6.62 \times 1 0^{- 34} J s$ , $e = 1.6 \times 1 0^{- 19} C$ and $c = 3 \times 1 0^{8} m/s)$
1. A.3.68
2. B.4.68
3. C.5.68
4. D.2.68
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Answer: C
Q432026 · 5 Apr 2026 · Shift 2
An electron is travelling with a velocity $v$ in free space and when it enters a medium, its velocity is reduced by $20%$ . The de Broglie wavelength of electron in the medium is $α λ_{0}$ , where $λ_{0}$ is its de Broglie wavelength in free space. The value of $α$ is ____.
1. A.1.20
2. B.1.0
3. C.1.25
4. D.0.75
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Answer: C
Q442026 · 5 Apr 2026 · Shift 2
Assuming the experimental mass of $_{06}^{12} C$ as $12 u$ , the mass defect of $_{06}^{12} C$ atom is ____ $MeV/ c^{2}$ . (Mass of proton $= 1.00727 u$ , mass of neutron $= 1.00866 u$ , $1 u = 931.5 MeV/ c^{2}$ and $c$ is the speed of the light in vacuum).
1. A.127.5
2. B.89.03
3. C.272.0
4. D.92.0
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Answer: B
Q292026 · 4 Apr 2026 · Shift 1
Two nuclei of mass number 3 combine with another nucleus of mass number 4 to yield a nucleus of mass number 10. If the binding energy per nucleon for the mass numbers 3, 4 and 10 are $5.6 MeV$ , $7.4 MeV$ and $6.1 MeV$ , respectively, then in the process, $Δ M c^{2} =$ _________ $MeV$ .
1. A.6.9
2. B.7.9
3. C.2.2
4. D.4.3
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Answer: C
Q262026 · 4 Apr 2026 · Shift 2
Match the LIST-I with LIST-II $A. B. C. D. List-I Planck’s constant Stopping potential Work function Threshold frequency I. II. III. IV. List-II M L^{2} T^{- 2} T^{- 1} M L^{2} T^{- 1} M L^{2} T^{- 3} A^{- 1}$ Choose the correct answer from the options given below:
1. A.A-III, B-IV, C-I, D-II
2. B.A-I, B-II, C-III, D-IV
3. C.A-IV, B-III, C-I, D-II
4. D.A-I, B-IV, C-III, D-II
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Answer: A
Q432026 · 4 Apr 2026 · Shift 2
In Rutherford's alpha-particle scattering experiment, only a few alpha particles rebound back because A. The size of gold nucleus is very small as compared to the size of gold atom. B. Alpha particle and gold nucleus have equal charge. C. The impact parameter is minimum for a few alpha particles. D. A few alpha particles have very high kinetic energy. E. Only a few alpha particles undergo head-on collision with the nuclei. Choose the correct answer from the options given below:
1. A.A, B Only
2. B.B, E Only
3. C.C, D Only
4. D.A, C, E Only
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Answer: D
Q442026 · 4 Apr 2026 · Shift 2
The de Broglie wavelength associated with an electron accelerated through a potential difference $V$ is $λ_{e}$ and the de Broglie wavelength associated with a proton accelerated through the same potential difference is $λ_{p}$ . If their corresponding masses are $m_{e}$ and $m_{p}$ , respectively, then the ratio of their de Broglie wavelengths $(\frac{λ _{e}}{λ _{p}})$ is ____.
1. A. $\frac{m _{p}}{m _{e}}$
2. B. $\frac{m _{e}}{m _{p}}$
3. C. $\frac{m _{p}}{m _{e}}$
4. D. $(\frac{m _{p}}{m _{e}})^{2}$
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Answer: A
Q422026 · 2 Apr 2026 · Shift 1
For a certain metal, when monochromatic light of wavelength $λ$ is incident, the stopping potential for photoelectrons is $3 V_{o}$ . When the same metal is illuminated by light of wavelength $2 λ$ , then the stopping potential becomes $V_{o}$ . The threshold wavelength for photoelectric emission for the given metal is $α λ$ . The value of $α$ is ____.
1. A.1
2. B.4
3. C.2
4. D.3
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Answer: B
Q442026 · 2 Apr 2026 · Shift 2
The binding energy per nucleon of $_{83}^{209} Bi$ is ____ $MeV$ . $[Take m (_{83}^{209} Bi) = 208.980388 u, m_{p} = 1.007825 u, m_{n} = 1.008665 u, 1 u = 931 MeV/ c^{2}]$
1. A.7.48
2. B.7.84
3. C.8.79
4. D.6.94
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Answer: B
Q472026 · 2 Apr 2026 · Shift 2· Numerical answer
Using Bohr's model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the $2^{nd}$ and $4^{th}$ orbits of hydrogen atom ____.
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Answer: 32
Q322026 · 28 Jan 2026 · Shift 1
An atom $_{3}^{8} X$ is bombarded by shower of fundamental particles and in $10 s$ this atom absorbed $10$ electrons, $10$ protons and $9$ neutrons. The percentage growth in the surface area of the nucleons is recorded by :
1. A. $150%$
2. B. $900%$
3. C. $125%$
4. D. $225%$
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Answer: C
Q502026 · 28 Jan 2026 · Shift 1· Numerical answer
The ratio of de Broglie wavelength of a deuteron with kinetic energy $E$ to that of an alpha particle with kinetic energy $2 E$ , is $n : 1$ . The value of $n$ is ____ . (Assume mass of proton $=$ mass of neutron)
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Answer: 2
Q392026 · 28 Jan 2026 · Shift 2
A nucleus has mass number $α$ and radius $R_{α}$ . Another nucleus has mass number $β$ and radius $R_{β}$ . If $β = 8 α$ then $R_{α} / R_{β}$ is :
1. A.1
2. B.2
3. C.8
4. D.0.5
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Answer: D
Q442026 · 28 Jan 2026 · Shift 2
Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is ________. $(Given : h = 6.63 \times 1 0^{- 34} J.s and c = 3 \times 1 0^{8} m/s)$
1. A. $10 \times 1 0^{15}$
2. B. $5 \times 1 0^{16}$
3. C. $5 \times 1 0^{15}$
4. D. $2 \times 1 0^{16}$
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Answer: D
Q312026 · 24 Jan 2026 · Shift 1
Match the LIST-I with LIST-II $List-I A. B. C. D. Radio-wave Micro-wave Infrared-wave X-ray List-II I. II. III. IV. is produced by Magnetron valve due to change in the vibrational modes of atoms due to inner shell electrons moving from higher energy level to lower energy level due to rapid acceleration of electrons$ Choose the correct answer from the options given below:
1. A.A-IV, B-II, C-I, D-III
2. B.A-IV, B-III, C-I, D-II
3. C.A-IV, B-I, C-II, D-III
4. D.A-II, B-IV, C-III, D-I
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Answer: C
Q362026 · 24 Jan 2026 · Shift 1
Given below are two statements : Statement I : For all elements, greater the mass of the nucleus, greater is the binding energy per nucleon. Statement II : For all elements, nuclei with less binding energy per nucleon transforms to nuclei with greater binding energy per nucleon. In the light of the above statements, choose the correct answer from the options given below
1. A.Statement I is false but Statement II is true
2. B.Both Statement I and Statement II are true
3. C.Both Statement I and Statement II are false
4. D.Statement I is true but Statement II is false
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Answer: A
Q272026 · 23 Jan 2026 · Shift 1
The de Broglie wavelength of an oxygen molecule at $2 7^{\circ} C$ is $x \times 1 0^{- 12} m$ . The value of $x$ is (take Planck's constant $= 6.63 \times 1 0^{- 34} J s$ , Boltzmann constant $= 1.38 \times 1 0^{- 23} J/K$ , mass of oxygen molecule $= 5.31 \times 1 0^{- 26} kg$ )
1. A.24
2. B.30
3. C.20
4. D.26
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Answer: D
Q352026 · 23 Jan 2026 · Shift 1
In hydrogen atom spectrum, ( $R \to$ Rydberg's constant) A. the maximum wavelength of the radiation of Lyman series is $\frac{4}{3 R}$ B. the Balmer series lies in the visible region of the spectrum C. the minimum wavelength of the radiation of Paschen series is $\frac{9}{R}$ D. the minimum wavelength of Lyman series is $\frac{5}{4 R}$ Choose the correct answer from the options given below :
1. A.A, B Only
2. B.B, D Only
3. C.A, B and D Only
4. D.A, B and C Only
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Answer: D
Q372026 · 23 Jan 2026 · Shift 2
Which of the following pair of nuclei are isobars of the element?
1. A. $_{1}^{3} H$ and $_{2}^{3} He$
2. B. $_{80}^{198} Hg$ and $_{79}^{197} Au$
3. C. $_{1}^{2} H$ and $_{1}^{3} H$
4. D. $_{92}^{236} U$ and $_{92}^{238} U$
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Answer: A