Q.No:1 JAM-2015
A system comprises of three electrons. There are three single particle energy levels accessible to
each of these electrons. The number of possible configurations for this system is
(A)
\(1\)
(B)
\(3\)
(C)
\(6\)
(D)
\(7\)
Check Answer
Option D
Q.No:2 JAM-2015
Vibrations of diatomic molecules can be represented as those of harmonic oscillators. Two halogen molecules \(X_2\) and \(Y_2\) have fundamental vibrational frequencies \(v_X=16.7\times 10^{12}\) Hz and \(v_Y=26.8\times 10^{12}\) respectively. The respective force constants are \(K_X=325\) N/m and \(K_Y=446\) N/m. The atomic masses of \(F\), \(Cl\) and \(Br\) are 19.0, 35.5 and 79.9 atomic mass unit respectively. The halogen molecules \(X_2\) and \(Y_2\) are
(A)
\(X_2=F_2\) and \(Y_2=Cl_2\)
(B)
\(X_2=Cl_2\) and \(Y_2=F_2\)
(C)
\(X_2=Br_2\) and \(Y_2=F_2\)
(D)
\(X_2=F_2\) and \(Y_2=Br_2\)
Check Answer
Option B
Q.No:3 JAM-2015
A nucleus has a size of \(10^{-15}\)m. Consider an electron bound within a nucleus. The estimated energy of this electron is of the order of
(A)
\(1\) MeV
(B)
\(10^2\) MeV
(C)
\(10^4\) MeV
(D)
\(10^6\) MeV
Check Answer
Option B
Q.No:4 JAM-2015
In the hydrogen atom spectrum, the ratio of the longest wavelength in the Lyman series (final state n = 1) to that in the Balmer series (final state n = 2) is _____________.
Check Answer
Ans 0.16-0.20
Q.No:5 JAM-2016
Consider a free electron \((e)\) and a photon (ph) both having 10 eV of energy. If \(\lambda\) and \(P\) represent wavelength and momentum respectively, then
(mass of electron = \(9.1 \times 10^{-31}\) kg; speed of light = \(3 \times 10^8\) m/s)
(A)
\(\lambda_e=\lambda_{ph}\) and \(P_e=P_{ph}\)
(B)
\(\lambda_e=P_{ph}\)
(C)
\(\lambda_e>\lambda_{ph}\) and \(P_e<P_{ph}\)
(D)
\(\lambda_e<\lambda_{ph}\) and \(P_e<P_{ph}\)
Check Answer
Option B
Q.No:6 JAM-2016
In a photoelectric experiment both sodium (work function = 2.3 eV) and tungsten (work function =4.5 eV) metals were illuminated by an ultraviolet light of same wavelength. If the stopping
potential for tungsten is measured to be 1.8 V, the value of the stopping potential for sodium will be _______________ V.
Check Answer
Ans 4
Q.No:7 JAM-2017
Consider Rydberg (hydrogen-like) atoms in a highly excited state with \(n\) around \(300\) .The wavelength of radiation coming out of these atoms for transitions to the adjacent states lies in the range:
(A)
Gamma rays \((\lambda \sim pm)\)
(B)
UV \((\lambda \sim nm)\)
(C)
Infrared \((\lambda \sim \mu m)\)
(D)
RF \((\lambda \sim m)\)
Check Answer
Option D
Q.No:8 JAM-2017
For an atomic nucleus with atomic number \(Z\) and mass number \(A\) , which of the following is (are) correct?
(A)
Nuclear matter and nuclear charge are distributed identically in the nuclear volume
(B)
Nuclei with \(Z>83\) and \(A>209\) emit \(\alpha\)-radiation
(C)
The surface contribution to the binding energy is proportional to \(A^{2/3}\)
(D)
\(\beta\)-decay occurs when the proton to neutron ratio is large, but not when it is small
Check Answer
Option B,C OR A,B,C
Q.No:10 JAM-2018
Let \(T_g\) and \(T_e\) be the kinetic energies of the electron in the ground and the third excited states of a hydrogen atom, respectively. According to the Bohr model, the ratio \(T_g/T_e\) is
(A)
\(3\)
(B)
\(4\)
(C)
\(9\)
(D)
\(16\)
Check Answer
Option D
Q.No:11 JAM-2018
The mean momentum \(\bar{p}\) of a nucleon in a nucleus of mass number \(A\) and atomic number \(Z\) depends on \(A\), \(Z\) as
(A)
\(\bar{p}\propto A^{\frac{1}{3}}\)
(B)
\(\bar{p}\propto Z^{\frac{1}{3}}\)
(C)
\(\bar{p}\propto A^{-\frac{1}{3}}\)
(D)
\(\bar{p}\propto AZ^{-\frac{2}{3}}\)
Check Answer
Option C
Q.No:12 JAM-2019
In the thermal neutron induced fission of \(^{235} U\), the distribution of relative number of the observed fission fragments (Yield) versus mass number (A) is given by
Check Answer
Option A
Q.No:13 JAM-2019
The relation between the nuclear radius \((R)\) and the mass number \((A)\), given by \(R=1.2 A^{1/3}\) fm, implies that
(A)
The central density of nuclei is independent of \(A\)
(B)
The volume energy per nucleon is a constant
(C)
The attractive part of the nuclear force has a long range
(D)
The nuclear force is charge dependent
Check Answer
Option A,B
Q.No:14 JAM-2019
If the wavelength of \(K\alpha_2\) X-ray line of an element is \(1.544\) Angstrom, then the atomic number (Z) of the element is __________________.
(Rydberg constant \(R=1.097 \times 10^7 m^{-1}\) and velocity of light \(c=3 \times 10^8\) m/s)
Check Answer
Ans 29
Q.No:15 JAM-2019
A proton is confined within a nucleus of size \(10^{-13}\) cm. The uncertainty in its velocity is __________________ \(10^8\) m/s.
(Round off to 2 decimal places)
(Planck’s constant \(h=6.626\times 10^{-34}\)J s and proton mass \(m_p=1.672 \times 10^{-27}\) kg)
Check Answer
Ans 0.30-3.97
Q.No:16 JAM-2020
A collimated beam of laser light of wavelength 514 nm is normally incident on a smooth glass slab placed in air. Given the refractive indices of glass and air are 1.47 and 1.0, respectively, the percentage of light intensity reflected back is
(A)
0
(B)
4.0
(C)
3.6
(D)
4.2
Check Answer
Option C
Q.No:17 JAM-2020
The radioactive nuclei \(^{40}K\) decay to \(^{40} Ar\) with a half-life of \(1.25 \times 10^9\) years. The \(^{40}K / ^{40} Ar\) isotopic
ratio for a particular rock is found to be 50. The age of the rock is \(m \times 10^7\). years. The value of \(m\) is ___________________ . (Round off to 2 decimal place)
Check Answer
Ans 3.55-3.65
Q.No:18 JAM-2021
The wavelength of characteristic \(K_\alpha\) X-ray photons from \(M_0\) (atomic number 42) is _________________ Angstrom. (Round off to one decimal place).
(speed of light is \(3 \times 10^8\) m/s; Rydberg constant \(R\)= \(1.09 \times 10^7/\)m)
Check Answer
Ans 0.6-0.8
Q.No:19 JAM-2022
Consider the Bohr model of hydrogen atom. The speed of an electron in the
second orbit \((n=2)\) is ____________________ \(\times 10^6\) m/s (Round off to 2 decimal places).
(Use \(h=6.63\times 10^{-34}\)Js , \(e=1.6 \times 10^{-19}\)C, \(\epsilon_0=8.85 \times 10^{-12} C^2 m^2/N\))
Check Answer
Ans 1.08-1.10
Q.No:20 JAM-2015
The variation of binding energy per nucleon with respect to the mass number of nuclei is shown in the figure.
Consider the following reactions:
(1) \(^{238}_{92}U\rightarrow ^{206}_{82}Pb+10p+22n \)
(2) \(^{238}_{92}U\rightarrow ^{206}_{82}Pb+8 ^4 _2 He+6 \hspace{1mm}e^- \)
Which one of the following statements is true for the given decay modes of \(^{238}_{92}U\) ?
(A)
Both (1) and (2) are allowed
(B)
Both (1) and (2) are forbidden
(C)
(1) is forbidden and (2) is allowed
(D)
(1) is allowed and (2) is forbidden
Check Answer
Option C
Q.No:21 JAM-2015
Muons are elementary particles produced in the upper atmosphere. They have a life time of \(2.2\mu\)s. Consider muons which are traveling vertically towards the earth’s surface at a speed of 0.0998c. For an observer on earth, the height of the atmosphere above the surface of the earth is 10.4 km. Which
of the following statements are true?
(A)
The muons can never reach earth’s surface
(B)
The apparent thickness of earth’s atmosphere in muon’s frame of reference is 0.96 km
(C)
The lifetime of muons in earth’s frame of reference is \(34.8\mu\)s
(D)
Muons traveling at a speed greater than 0.998c reach the earth’s surface
Check Answer
Option C,D
Q.No:22 JAM-2016
A particular radioisotope has a half-life of \(5\) days. In \(15\) days the probability of decay in percentage will be __________________.
Check Answer
Ans 87-88
Q.No:23 JAM-2019
An atomic nucleus \(X\) with half-life \(T_X\) decays to a nucleus \(Y\), which has half-life \(T_Y\). The condition(s) for secular equilibrium is(are)
(A)
\(T_X \simeq T_Y\)
(B)
\(T_X < T_Y\)
(C)
\(T_X \ll T_Y\)
(D)
\(T_X \gg T_Y\)
Check Answer
Option D
Q.No:24 JAM-2019
In a typical human body, the amount of radioactive \(^{40}K\) is \(3.24 \times 10^{-5}\) percent of its mass. The activity due to \(^{40}K\) in a human body of mass 70 kg is ________________ kBq.
(Half-life of \(^{40}K=3.924 \times 10^{16}\) s, Avogadro’s number \(N_A=6.022 \times 10^{23} mol^{-1}\))
Check Answer
Ans 5.95-6.01
Q.No:25 JAM-2023
An \(\alpha\) particle with energy of 3 MeV is moving towards a nucleus of \(^{50} Sn\). Its minimum distance of approach to the nucleus is \(f\times 10^{-14}\) m. The value of \(f\) is _________ (rounded off to one decimal place).
Check Answer
Ans 4.7- 4.9
Q.No:26 JAM-2023
Consider the \(\alpha\)-decay \(^{90} Th ^{232} \to ^{88} Ra ^{228}\). In an experiment with one gram of \(^{90} Th ^{232}\), the average count rate (integrated over the entire volume) measured by the \(\alpha\)-detector is 3000 counts \(s^{-1}\). If the half life of \(^{90} Th ^{232}\) is given as \(4.4 \times 10^{17}\)s, then the efficiency of the \(\alpha\)-detector is _________ (rounded off to two decimal
places).
Check Answer
Ans 0.72- 0.74
Q.No:27 JAM-2024
The magnitudes of spin magnetic moments of electron, proton and neutron are \(\mu_e\), \(\mu_p\) and \(\mu_n\), respectively. Then,
A) \(\mu_e > \mu_p > \mu_n\)
B) \(\mu_e = \mu_p > \mu_n\)
C) \(\mu_e < \mu_p < \mu_n\)
D) \(\mu_e < \mu_p = \mu_n\)
Check Answer
Option A
Q.No:28 JAM-2024
A stationary nitrogen (\( ^{14}_{7}N \)) nucleus is bombarded with \( \alpha \)-particle (\( ^{4}_{2}He \)) and the following nuclear reaction takes place:
\[ ^{4}_{2}He \hspace{5mm} + ^{14}_{7}N \hspace{5mm} \rightarrow \hspace{5mm} ^{17}_{8}O \hspace{5mm} + ^{1}_{1}H\]
Mass: \( 4.003u \) \( \hspace{3mm} \) \( 14.003u \) \(\hspace{3mm}\) \( 16.999u \) \( \hspace{3mm} \) \( 1.008u \)
If the kinetic energies of \( ^{4}_{2}He \) and \( ^{1}_{1}H \) are \( 5.314MeV \) and \( 4.012MeV \), respectively, then the kinetic energy of \( ^{17}_{8}O \) is _____ MeV. (Rounded off to one decimal place)
(Masses are given in units of \( u = 931.5MeV/c^2 \))