JEE Advanced
2026
MCQ
A nuclear reactor starts producing a radioactive nuclide X from t = 0, at a constant rate of α per second. Each decay of X produces energy E0, which is utilized to heat a liquid of mass m and specific heat s. Assuming no heat loss from the liquid and taking λ as the decay constant of X, the rate of increase in the temperature of the liquid is :
JEE Advanced
2026
MSQ
Consider a hydrogen atom with $v_k, r_k,$ and $K_k$ denoting the velocity, orbital radius and kinetic energy of the electron in the $k^{{th}}$ orbit, respectively. The electron undergoes a transition from the $n^{{th}}$ orbit, emitting radiation corresponding to the Lyman series. Considering $h$ to be the Planck’s constant and $
ho_0$ the permittivity of the free space, the correct statement(s) is/are:
JEE Advanced
2025
MCQ
List-I shows various functional dependencies of energy $(E)$ on the atomic number $(Z)$. Energies associated with certain phenomena are given in List-II.
Choose the option that describes the correct match between the entries in List-I to those in List-II.
| List–I |
List–II |
| (P) $E \propto Z^2$ |
(1) energy of characteristic x-rays |
| (Q) $E \propto (Z - 1)^2$ |
(2) electrostatic part of the nuclear binding energy for stable nuclei with mass numbers in the range 30 to 170 |
| (R) $E \propto Z(Z - 1)$ |
(3) energy of continuous x-rays |
| (S) $E$ is practically independent of $Z$ |
(4) average nuclear binding energy per nucleon for stable nuclei with mass number in the range 30 to 170 |
|
(5) energy of radiation due to electronic transitions from hydrogen-like atoms |
JEE Advanced
2024
MSQ
A particle of mass $m$ is moving in a circular orbit under the influence of the central force $F(r)=-k r$, corresponding to the potential energy $V(r)=k r^2 / 2$, where $k$ is a positive force constant and $r$ is the radial distance from the origin. According to the Bohr's quantization rule, the angular momentum of the particle is given by $L=n \hbar$, where $\hbar=h /(2 \pi), h$ is the Planck's constant, and $n$ a positive integer. If $v$ and $E$ are the speed and total energy of the particle, respectively, then which of the following expression(s) is(are) correct?
JEE Advanced
2023
MCQ
List-I shows different radioactive decay processes and List-II provides possible emitted particles. Match each entry in List-I with an appropriate entry from List-II, and choose the correct option.
| List - I |
List - II |
| (P) ${ }_{92}^{238} U \rightarrow{ }_{91}^{234} \mathrm{~Pa}$ |
(1) one $\alpha$ particle and one $\beta^{+}$particle |
| (Q) ${ }_{82}^{214} \mathrm{~Pb} \rightarrow{ }_{82}^{210} \mathrm{~Pb}$ |
(2) three $\beta^{-}$particles and one $\alpha$ particle |
| (R) ${ }_{81}^{210} \mathrm{Tl} \rightarrow{ }_{82}^{206} \mathrm{~Pb}$ |
(3) two $\beta^{-}$particles and one $\alpha$ particle |
| (S) ${ }_{91}^{228} \mathrm{~Pa} \rightarrow{ }_{88}^{224} \mathrm{Ra}$ |
(4) one $\alpha$ particle and one $\beta^{-}$particle |
|
(5) one $\alpha$ particle and two $\beta^{+}$particles |
JEE Advanced
2022
MSQ
The binding energy of nucleons in a nucleus can be affected by the pairwise Coulomb repulsion. Assume that all nucleons are uniformly distributed inside the nucleus. Let the binding energy of a proton be $E_{b}^{p}$ and the binding energy of a neutron be $E_{b}^{n}$ in the nucleus.
Which of the following statement(s) is(are) correct?
JEE Advanced
2021
MCQ
A heavy nucleus Q of half-life 20 minutes undergoes alpha-decay with probability of 60% and beta-decay with probability of 40%. Initially, the number of Q nuclei is 1000. The number of alpha-decays of Q in the first one hour is
JEE Advanced
2021
MSQ
A heavy nucleus N, at rest, undergoes fission N $\to$ P + Q, where P and Q are two lighter nuclei. Let $\delta$ = MN $-$ MP $-$ MQ, where MP, MQ and MN are the masses of P, Q and N, respectively. EP and EQ are the kinetic energies of P and Q, respectively. The speeds of P and Q are vP and vQ, respectively. If c is the speed of light, which of the following statement(s) is(are) correct?
JEE Advanced
2021
MSQ
Which of the following statement(s) is(are) correct about the spectrum of the hydrogen atom?
JEE Advanced
2020
MSQ
In an X-ray tube, electrons emitted from a filament (cathode) carrying current I hit a target (anode) at a distance d from the cathode. The target is kept at a potential V higher than the cathode resulting in emission of continuous and characteristic X-rays. If the filament current I is decreased to ${1 \over 2}$, the potential difference V is increased to 2V, and the separation distance d is reduced to ${d \over 2}$, then
JEE Advanced
2020
MSQ
A particle of mass m moves in circular orbits with potential energy V(r) = Fr, where F is a positive
constant and r is its distance from the origin. Its energies are calculated using the Bohr model. If the
radius of the particle’s orbit is denoted by R and its speed and energy are denoted by v and E,
respectively, then for the nth orbit (here h is the Planck’s constant)
JEE Advanced
2019
MCQ
In a radioactive sample, ${}_{19}^{40}K$ nuclei either decay into stable ${}_{20}^{40}Ca$ nuclei with decay constant 4.5 $ \times $ 10-10 per year or into stable ${}_{18}^{40}Ar$ nuclei with decay constant 0.5 $ \times $ 10-10 per year. Given that in this sample all the stable ${}_{20}^{40}Ca$ and ${}_{18}^{40}Ar$ nuclei are produced by the ${}_{19}^{40}K$ nuclei only. In time t $ \times $ 109 years, if the ratio of the sum of stable ${}_{20}^{40}Ca$ and ${}_{18}^{40}Ar$ nuclei to the radioactive ${}_{19}^{40}K$ nuclei is 99, the value of t will be
[Given : In 10 = 2.3]
JEE Advanced
2019
MSQ
A free hydrogen atom after absorbing a photon of wavelength $\lambda $a gets excited from the state n = 1 to the state n = 4. Immediately after that the electron jumps to n = m state by emitting a photon of wavelength $\lambda $e. Let the change in momentum of atom due to the absorption and the emission be $\Delta {p_a}$ and $\Delta {p_e}$, respectively. If ${{{\lambda _a}} \over {{\lambda _e}}} = {1 \over 5}$, which of the option(s) is/are correct? [Use hc = 1242 eVnm; 1 nm = 10-9 m, h and c are Planck's constant and speed of light in vacuum, respectively]
JEE Advanced
2018
MSQ
In a radioactive decay chain, ${}_{90}^{232}Th$ nucleus decays to ${}_{82}^{212}Pb$ nucleus. Let ${N_\alpha }$ and ${N_\beta }$ be the number of $\alpha $ and ${\beta ^ - }$ particles, respectively, emitted in this decay process. Which of the following statements is (are) true?
JEE Advanced
2016
MCQ
An accident in a nuclear laboratory resulted in deposition of a certain amount of radioactive material of half-life 18 days inside the laboratory. Tests revealed that the radiation was 64 times more than the permissible level required for safe operation of the laboratory. What is the minimum number of days after which the laboratory can be considered safe for use?
JEE Advanced
2016
MCQ
The electrostatic energy of Z protons uniformly distributed throughout a spherical nucleus of radius R is given by $E = {3 \over 5}{{Z(Z - 1){e^2}} \over {4\pi {\varepsilon _0}R}}$
The measured masses of the neutron, $_1^1H$, $_7^{15}N$ and $_8^{15}O$ are 1.008665u, 1.007825u, 15.000109u and 15.003065u, respectively. Given that the radii of both the $_7^{15}N$ and $_8^{15}O$ nuclei are same, 1 u = 931.5 MeV/c2 (c is the speed of light) and e2/(4$\pi$${{\varepsilon _0}}$) = 1.44 MeV fm. Assuming that the difference between the binding energies of $_7^{15}N$ and $_8^{15}O$ is purely due to the electrostatic energy, the radius of either of the nuclei is (1 fm = 10$-$15 m)
JEE Advanced
2016
MSQ
Highly excited states for hydrogen-like atoms (also called Rydberg states) with nuclear charge Ze are defined by their principle quantum number n, where n >> 1. Which of the following statement(s) is(are) true?
JEE Advanced
2015
MCQ
Match the nuclear processes given in Column I with the
appropriate option(s) in Column II:

JEE Advanced
2015
MCQ
A fission reaction is given by $_{92}^{236}U \to _{54}^{140}Xe + _{38}^{94}Sr + x + y$, where x and y are two particles. Considering $_{92}^{236}U$ to be at rest, the kinetic energies of the products are denoted by ${K_{Xe}},{K_{Sr}},{K_x}(2MeV)$ $
\text { and } \mathrm{K}_{\mathrm{y}}(2 \mathrm{MeV})
$, respectively. Let the binding energies per nucleon of $_{92}^{236}U$, $_{54}^{140}Xe$ and $_{38}^{94}Sr$ be 7.5 MeV, 8.5 MeV and 8.5 MeV, respectively. Considering different conservation laws, the correct options is/are
JEE Advanced
2014
MCQ
If $\lambda$Cu is the wavelength of K$\alpha$ X-ray line of copper (atomic number 29) and $\lambda$Mo is the wavelength of the K$\alpha$ X-ray line of molybdenum (atomic number 42), then the ratio $\lambda$Cu/$\lambda$Mo is close to
JEE Advanced
2013
MCQ
The kinetic energy (in keV) of the alpha particle, when the nucleus $_{84}^{210}Po$ at rest undergoes alpha decay, is
JEE Advanced
2013
MCQ
Match List I of the nuclear processes with List II containing parent nucleus and one of the end products of each process and then select the correct answer using the codes given below the lists :
|
List I |
|
List II |
| P. |
Alpha decay |
1. |
$_8^{15}O \to _7^{15}N + ...$
|
| Q. |
${\beta ^ + }$ decay |
2. |
$_{91}^{238}U \to _{90}^{234}Th + ...$
|
| R. |
Fission |
3. |
$_{83}^{185}Bi \to _{82}^{184}Pb + ...$
|
| S. |
Proton emission |
4. |
$_{94}^{239}Pu \to _{57}^{140}La + ...$
|
JEE Advanced
2013
MSQ
The radius of the orbit of an electron in a hydrogen-like atom is 4.5a0, where a0 is the Bohr radius. Its orbital angular momentum is ${{3h} \over {2\pi }}$. It is given that h is Planck constant and R is Rydberg constant. The possible wavelength(s), when the atom de-excites, is(are)
JEE Advanced
2012
MCQ
What is the maximum energy of the anti-neutrino?
JEE Advanced
2012
MCQ
If the anti-neutrino had a mass of 3 eV/c2 (where c is the speed of light) instead of zero mass, what should be the range of the kinetic energy, K, of the electron?
JEE Advanced
2011
MCQ
The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 $\mathop A\limits^o $. The wavelength of the second spectral line in the Balmer series of singly-ionized helium atom is
JEE Advanced
2010
MCQ
A diatomic molecule has moment of inertia I. By Bohr's quantization condition, its rotational energy in the nth level (n = 0 is not allowed) is
JEE Advanced
2010
MCQ
It is found that the excitation frequency from ground to the first excited state of rotation for the CO molecule is close to ${4 \over \pi } \times {10^{11}}$ Hz. Then, the moment of inertia of CO molecule about its centre of mass is close to (Take h = 2$\pi$ $\times$ 10$-$34 J-s)
JEE Advanced
2010
MCQ
In a CO molecule, the distance between C (mass = 12 amu) and O (mass = 16 amu), where 1 amu $ = {5 \over 3} \times {10^{ - 27}}$ kg, is close to :
JEE Advanced
2009
MCQ
The speed of the particle, that can take discrete values, is proportional to
JEE Advanced
2009
MCQ
In the core of nuclear fusion reactor, the gas becomes plasma because of
JEE Advanced
2009
MCQ
Assume that two deuteron nuclei in the core of fusion reactor at temperature T are moving towards each other, each with kinetic energy 1.5 kT, when the separation between them is large enough to neglect Coulomb potential energy. Also neglect any interaction from other particles in the core. The minimum temperature T required for them to reach a separation of 4 $\times$ 10$^{-15}$ m is in the range
JEE Advanced
2009
MCQ
Results of calculations for four different designs of a fusion reactor using D-D reaction are given below. Which of these is most promising based on Lawson criterion?
JEE Advanced
2008
MCQ
A radioactive sample S1 having activity of 5 $\mu$Ci has twice the number of nuclei as another sample S2 which has an activity of 10 $\mu$Ci. The half lives of S1 and S2 can be :
JEE Advanced
2008
MCQ
The quantum number n of the state finally populated in He$^+$ ions is :
JEE Advanced
2008
MCQ
The wavelength of light emitted in the visible region by He$^+$ ions after collisions with H atoms is
JEE Advanced
2008
MCQ
The ratio of the kinetic energy of the $n=2$ electron for the H atom to that of He$^+$ ion is
JEE Advanced
2008
MSQ
Assume that the nuclear binding energy per nucleon (B/A) versus mass number (A) is as shown in the figure. Use this plot to choose the correct choice(s) given below.

JEE Advanced
2007
MCQ
In the option given below, let E denote the rest mass energy of a nucleus and n a neutron. The correct option is
JEE Advanced
2007
MCQ
The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is
JEE Advanced
2006
MCQ
$ \text { Match the following Columns. } $
| Column I |
Column II |
| (A) |
Nuclear fusion. |
(P) |
Converts some matter into energy. |
| (B) |
Nuclear fission. |
(Q) |
Generally possible for nuclei with low atomic number. |
| (C) |
$\beta$-decay. |
(R) |
Generally possible for nuclei with higher atomic number. |
| (D) |
Exothermic nuclear reaction. |
(S) |
Essentially proceeds by weak nuclear forces. |
JEE Advanced
2005
MCQ
Highly energetic electrons are bombarded on a target of an element containing 30 neutrons. The ratio of radii of nucleus to that of Helium nucleus is $(14)^{\frac{1}{3}}$. Find
(A) Atomic number of the nucleus;
(B) the frequency of $\mathrm{K}_{\alpha}$ line of the X-ray produced.
$\left(\mathrm{R}=1.1 \times 10^{7} \mathrm{~m}^{-1}\right.$ and $\left.c=3 \times 10^{8} \mathrm{~m} / \mathrm{s}\right)$