← Back to Physics

Atoms and Nuclei

132 Questions Start NEET Test
All Exams NEET AIIMS
2014 Q51 NEET MCQ
10 Mar 2026
A radioactive X with a half life 1.4 $ \times $ 109 years decays to Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 1 : 7. The age of the rock is
A.
1.96 $ \times $ 109 years
B.
3.92 $ \times $ 109 years
C.
4.20 $ \times $ 109 years
D.
8.40 $ \times $ 109 years
2013 Q52 NEET MCQ
10 Mar 2026
$\alpha $-particles, $\beta $-particles and $\gamma $-rays are all having same energy. Their penetrating power in a given medium in increasing order will be
A.
$\gamma $, $\alpha $, $\beta $
B.
$\alpha $, $\beta $, $\gamma $
C.
$\beta $, $\alpha $, $\gamma $
D.
$\beta $, $\gamma $, $\alpha $
2013 Q53 NEET MCQ
10 Mar 2026
An electron in hydrogen atom makes a transition n1 $ \to $ n2 where n1 and n2 are principal quantum numbers of the two states . Assuming Bohr's model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible values of n1 and n2 are
A.
n1 = 6 and n2 = 2
B.
n1 = 8 and n2 = 1
C.
n1 = 8 and n2 = 2
D.
n1 = 4 and n2 = 2
2013 Q54 NEET MCQ
10 Mar 2026
How does the Binding Energy per nucleon vary with the increase in the number of nucleons ?
A.
Decrease continuously with mass number.
B.
First decreases and then increases with increase in mass number.
C.
First increases and then decreases with increase in mass number.
D.
increases continuously with mass number.
2013 Q55 NEET MCQ
10 Mar 2026
Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is
A.
${7 \over {29}}$
B.
${9 \over {31}}$
C.
${5 \over {27}}$
D.
${3 \over {23}}$
2013 Q56 NEET MCQ
10 Mar 2026
A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is (given 1 u = 931 MeV)
A.
6.675 MeV
B.
13.35 MeV
C.
2.67 MeV
D.
26.7 MeV
2013 Q57 NEET MCQ
10 Mar 2026
The half life of a radioactive isotope 'X' is 20 years. It decays to another element 'Y' which is stable. The two elements 'X' and 'Y' were found to be in the ratio 1 : 7 in a sample of a given rock. The age of the rock is estimated to be
A.
80 years
B.
100 years
C.
40 years
D.
60 years
2012 Q58 NEET MCQ
10 Mar 2026
The half life of a radioactive nucleus is 50 days. The time invertal (t2 $-$ t1) between the time t2 when ${2 \over 3}$ of it has decayed and the time t1 when ${1 \over 3}$ of it had decayed is
A.
30 days
B.
50 days
C.
60 days
D.
15 days
2012 Q59 NEET MCQ
10 Mar 2026
The transition from the state n = 3 to n = 1 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from
A.
2 $ \to $ 1
B.
3 $ \to $ 2
C.
4 $ \to $ 2
D.
4 $ \to $ 3
2012 Q60 NEET MCQ
10 Mar 2026
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be
A.
${{24hR} \over {25m}}$
B.
${{25hR} \over {24m}}$
C.
${{25m} \over {24hR}}$
D.
${{24m} \over {25hR}}$
2012 Q61 NEET MCQ
10 Mar 2026
Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelengths $\lambda $1 : $\lambda $2 emitted in the two cases is
A.
${7 \over 5}$
B.
${27 \over 20}$
C.
${27 \over 5}$
D.
${20 \over 7}$
2012 Q62 NEET MCQ
10 Mar 2026
A mixture consists of two radioactive materials A1 and A2 with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A1 and 160 g of A2. The amount of the two in the mixture will become equal after
A.
60 s
B.
80 s
C.
20 s
D.
40 s
2012 Q63 NEET MCQ
10 Mar 2026
If the nuclear radius of 27Al is 3.6 fermi, the approximate nuclear radius of 64Cu in fermi is
A.
2.4
B.
1.2
C.
4.8
D.
3.6
2011 Q64 NEET MCQ
10 Mar 2026
Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?
A.
0.65 eV
B.
1.9 eV
C.
11.1 eV
D.
13.6 eV
2011 Q65 NEET MCQ
10 Mar 2026
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0. number of P species are 4 N0 and that of Q are N0. Half -life of P (for conversion to R) is 1 minute where as that of Q is 2 minutes. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be
A.
2 N0
B.
3 N0
C.
${{9{N_0}} \over 2}$
D.
${{5{N_0}} \over 2}$
2011 Q66 NEET MCQ
10 Mar 2026
An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function 2.75 eV. If the stopping potential of the photoelectron is 10 V, then the value of n is
A.
2
B.
3
C.
4
D.
5
2011 Q67 NEET MCQ
10 Mar 2026
The half life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be
A.
150 years
B.
200 years
C.
250 years
D.
100 years
2011 Q68 NEET MCQ
10 Mar 2026
The power obtained in a reactor using U235 disintegration is 1000 kW. The mass decay of U235 per hour is
A.
10 microgram
B.
20 microgram
C.
40 microgram
D.
1 microgram
2011 Q69 NEET MCQ
10 Mar 2026
A radioactive nucleus of mass M emits a photon of frequency $v$ and the nucleus recoils. The recoil energy will be
A.
Mc2 $-$ h$v$
B.
h2$\upsilon $2/2Mc2
C.
zero
D.
h$v$
2011 Q70 NEET MCQ
10 Mar 2026
The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is
A.
3
B.
4
C.
1
D.
2
2011 Q71 NEET MCQ
10 Mar 2026
Fusion reaction takes place at high temperature because
A.
nuclei break up at high temperature
B.
atoms get ionised at high temperature
C.
kinetic energy is high enough to overcome the coulomb repulsion between nuclei
D.
molecules break up at high temperature
2011 Q72 NEET MCQ
10 Mar 2026
A nucleus ${}_n^mX$ emits one $\alpha $ particle and two $\beta $ particles. The resulting nucleus is
A.
${}_{n - 4}^{m - 6}Z$
B.
${}_n^{m - 6}Z$
C.
${}_n^{m - 4}X$
D.
${}_{n - 2}^{m - 4}Y$
2010 Q73 NEET MCQ
10 Mar 2026
The decay constant of a radio isotope is $\lambda $. If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which have decayed during the time (t1 $-$ t2)
A.
A1t1 $-$ A2t2
B.
A1 $-$ A2
C.
(A1 $-$ A2)/$\lambda $
D.
$\lambda ({A_1} - {A_2})$
2010 Q74 NEET MCQ
10 Mar 2026
The binding energy per nucleon in deuterium and helium nuclei are 1.1 MeV and 7.0 MeV, respectively. When two deuterium nuclei fuse to form a helium nucleus the energy released in the fusion is
A.
23.6 MeV
B.
2.2 MeV
C.
28.0 MeV
D.
30.2 MeV
2010 Q75 NEET MCQ
10 Mar 2026
The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) at which the activity reduces to half its value is
A.
${\log _e}{2 \over 5}$
B.
${5 \over {{{\log }_e}2}}$
C.
5log102
D.
5loge 2
2010 Q76 NEET MCQ
10 Mar 2026
An alpha nucleus of energy ${1 \over 2}$ mv2 bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
A.
${1 \over {Ze}}$
B.
v2
C.
${1 \over m}$
D.
${1 \over {{v_4}}}$
2010 Q77 NEET MCQ
10 Mar 2026
The mass of a ${}_3^7Li$ Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of ${}_3^7Li$ nucleus is nearly
A.
46 MeV
B.
5.6 MeV
C.
3.9 MeV
D.
23 MeV
2010 Q78 NEET MCQ
10 Mar 2026
The energy of a hydrogen atom in the ground state is $-$ 13.6 eV. The energy of a He+ ion in the first excited state will be
A.
$-$ 13.6 eV
B.
$-$ 27.2 eV
C.
$-$ 54.4 eV
D.
$-$ 6.8 eV
2010 Q79 NEET MCQ
10 Mar 2026
The energy of a hydrogen atom in the ground state is $-$ 13.6 eV. The energy of a He+ ion in the first excited state will be
A.
$-$ 13.6 eV
B.
$-$ 27.2 eV
C.
$-$ 54.4 eV
D.
$-$ 6.8 eV
2009 Q80 NEET MCQ
10 Mar 2026
In a Rutherford scattering experiment when a projectile of charge z1 and mass M1 approaches a target nucleus of charge z2 and mass M2, the distance of closest approach is r0. The energy of the projectile is
A.
directly proportional to z1z2
B.
inversely proportional to z1
C.
directly proportional to mass M1
D.
directly proportional to M1 $ \times $ M2
2009 Q81 NEET MCQ
10 Mar 2026
The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an
A.
isomer of parent
B.
isotone of parent
C.
isotope of parent
D.
isobar of parent
2009 Q82 NEET MCQ
10 Mar 2026
In the nuclear decay given below

${}_Z^AX \to {}_{Z + 1}^AY \to {}_{Z - 1}^{A - 4}B{}^ * \to {}_{Z - 1}^{A - 4}B,$

the particles emitted in the sequence are
A.
$\gamma $, $\beta $, $\alpha $
B.
$\beta $, $\gamma $, $\alpha $
C.
$\alpha $, $\beta $, $\gamma $
D.
$\beta $, $\alpha $, $\gamma $
2009 Q83 NEET MCQ
10 Mar 2026
The ionization energy of the electron in the hydrogen atom in its ground state is 13.6 eV. The atoms are excited to higher energy levels to emit radiations of 6 wavelengths, Maximum wavelength of emitted radiation corresponds to the transition between
A.
n = 3 to n = 1 states
B.
n = 2 to n = 1 states
C.
n = 4 to n = 3 states
D.
n = 3 to n = 2 states
2008 Q84 NEET MCQ
10 Mar 2026
Two radioactive materials X1 and X2 have decay constants $5\lambda $ and $\lambda $ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that X2 will be 1/e after a time
A.
1/4$\lambda $
B.
e/$\lambda $
C.
$\lambda $
D.
${1 \over 2}\lambda $
2008 Q85 NEET MCQ
10 Mar 2026
The ground state energy of hydrogen atom is $-$ 13.6 eV. When its electron is in the first excited state, its excitation energy is
A.
10.2 eV
B.
0
C.
3.4 eV
D.
6.8 eV
2008 Q86 NEET MCQ
10 Mar 2026
Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be
A.
${\left( 3 \right)^{1/3}}:1$
B.
1 : 1
C.
1 : 3
D.
3 : 1
2008 Q87 NEET MCQ
10 Mar 2026
If M(A; Z), Mp and Mn denote the masses of the nucleus ${}_Z^AX,$ proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represents its bonding energy in MeV, then
A.
M(A, Z) = ZMp + (A $-$ Z)Mn $-$ BE
B.
M(A, Z) = ZMp + (A $-$ Z)Mn + BE/c2
C.
M(A, Z) = ZMp + (A $-$ Z)Mn $-$ BE/c2
D.
M(A, Z) = ZMp + (A $-$ Z)Mn + BE
2007 Q88 NEET MCQ
10 Mar 2026
In a radioactive decay process, the negatively charged emitted $\beta $-particles are
A.
the electrons produced as a result of the decay of neutrons inside the nucleus
B.
the electrons produced as a result of collisions between atoms
C.
the electrons orbitting around the nucleus
D.
the electrons present inside the nucleus
2007 Q89 NEET MCQ
10 Mar 2026
If the nucleus ${}_{13}^{27}Al$ has a nuclear radius of about 3.6 fm, them ${}_{32}^{125}Te$ would have its radius approximately as
A.
9.6 fm
B.
12.0 fm
C.
4.8 fm
D.
6.0 fm
2007 Q90 NEET MCQ
10 Mar 2026
In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential $V$ and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio $\left( {{{ch\arg e\,\,on\,\,\,the\,\,ion\,\,} \over {mass\,\,of\,\,the\,\,ion}}} \right)$ will be proportional to
A.
1/R2
B.
R2
C.
R
D.
1/R
2007 Q91 NEET MCQ
10 Mar 2026
A nucleus ${}_Z^AX$ has mass represented by M(A, Z). If Mp and Mn denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then
A.
B.E. = [ZMp + (A $-$ Z)Mn $-$ M(A, Z)]c2
B.
B.E. = [ZMp + AMp $-$ M(A, Z)]c2
C.
B.E. = M(A, Z) $-$ ZMp $-$ (A $-$ Z)Mn
D.
B.E. = [M(A, Z) $-$ ZMp $-$ (A $-$ Z)Mn]c2
2007 Q92 NEET MCQ
10 Mar 2026
Two radioactive substances A and B have decay constants 5$\lambda $ and $\lambda $ respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be (1/e)2 after a time interval
A.
$4\lambda $
B.
$2\lambda $
C.
1/$2\lambda $
D.
1/$4\lambda $
2007 Q93 NEET MCQ
10 Mar 2026
The total energy of electron in the ground state of hydrogen atom is $-$ 13.6 eV. The kinetic energy of an electron in the first excited state is
A.
6.8 eV
B.
13.6 eV
C.
1.7 eV
D.
3.4 eV.
2006 Q94 NEET MCQ
10 Mar 2026
The radius of germanium (Ge) nuclide is measured to be twice the radius of ${}_4^9$Be. The number of nucleons in Ge are
A.
72
B.
73
C.
74
D.
75
2006 Q95 NEET MCQ
10 Mar 2026
In a radioactive material the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is $\lambda $, then
A.
R1 = R2
B.
R1 = R2e$-$$\lambda $(t1$-$t2)
C.
R1 = R2e$\lambda $(t1$-$t2)
D.
R1 = R2(t2/t1).
2006 Q96 NEET MCQ
10 Mar 2026
Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emited by hydrogen will be
A.
one
B.
two
C.
three
D.
four
2006 Q97 NEET MCQ
10 Mar 2026
The binding energy of deuteron is 2.2 MeV and that of ${}_2^4$He is 28 MeV. If two deuterons are fused to form one ${}_2^4$He then the energy released is
A.
30.2 MeV
B.
25.8 MeV
C.
23.6 MeV
D.
19.2 MeV
2005 Q98 NEET MCQ
10 Mar 2026
Which one of the following pairs of nuclei are isotones ?
A.
34Se74,  31Ga71
B.
38Sr84,  38Sr86
C.
42Mo92,   40Zr92
D.
20Ca40,  16S32
2005 Q99 NEET MCQ
10 Mar 2026
In any fission process the ratio
mass of fission products
mass of parent nucleus
 is
A.
equal to 1
B.
greater than 1
C.
less than 1
D.
depends on the mass of the parent nucleus.
2005 Q100 NEET MCQ
10 Mar 2026
In the reaction ${}_1^2$H + ${}_1^3$H $ \to $ ${}_2^4$He + ${}_0^1$n, if the binding
energies of ${}_1^2$ H, ${}_1^3$H and ${}_2^4$He are respectively a, b and c (in MeV),
then the energy (in MeV) released in this reaction is
A.
a + b + c
B.
a + b $-$ c
C.
c $-$ a $-$ b
D.
c + a $-$ b