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## Atoms and Nuclei

### Physics

#### Previous Years Questions

More
Mass numbers of two nuclei are in the ratio of $$4: 3$$. Their nuclear densities will be in the ratio of
JEE Main 2022 (Online) 26th July Evening Shift
A nucleus of mass $$M$$ at rest splits into two parts having masses $$\frac{M^{\prime}}{3}$$ and $${{2M'} \over 3}(M' ... JEE Main 2022 (Online) 26th July Evening Shift A parallel beam of light of wavelength$$900 \mathrm{~nm}$$and intensity$$100 \,\mathrm{Wm}^{-2}$$is incident on a su... JEE Main 2022 (Online) 26th July Morning Shift The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes la... JEE Main 2022 (Online) 26th July Morning Shift Hydrogen atom from excited state comes to the ground state by emitting a photon of wavelength$$\lambda$$. The value of ... JEE Main 2022 (Online) 25th July Evening Shift The ratio of wavelengths of proton and deuteron accelerated by potential Vp and Vd is 1 :$$\sqrt2$$. Then the ratio of ... JEE Main 2022 (Online) 25th July Evening Shift The momentum of an electron revolving in$$\mathrm{n}^{\text {th }}$$orbit is given by : (Symbols have their usual mean... JEE Main 2022 (Online) 25th July Morning Shift A hydrogen atom in ground state absorbs 12.09 eV of energy. The orbital angular momentum of the electron is increased by... JEE Main 2022 (Online) 30th June Morning Shift A cyclotron is working at a frequency of 10 MHz. If the radius of its dees is 60 cm. The maximum kinetic energy of accel... JEE Main 2022 (Online) 30th June Morning Shift Choose the correct option from the following options given below : JEE Main 2022 (Online) 24th June Morning Shift In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the elec... JEE Main 2022 (Online) 24th June Evening Shift The ratio for the speed of the electron in the 3rd orbit of He+ to the speed of the electron in the 3rd orbit of hydroge... JEE Main 2022 (Online) 25th June Morning Shift Which of the following figure represents the variation of$${l_n}\left( {{R \over {{R_0}}}} \right)$$with$${l_n}A$$(i... JEE Main 2022 (Online) 25th June Evening Shift A proton, a neutron, an electron and an$$\alpha$$particle have same energy. If$$\lambda$$p,$$\lambda$$n,$$\lambda$$... JEE Main 2022 (Online) 25th June Evening Shift A radioactive nucleus can decay by two different processes. Half-life for the first process is 3.0 hours while it is 4.5... JEE Main 2022 (Online) 26th June Evening Shift Which is the correct ascending order of wavelengths? JEE Main 2022 (Online) 26th June Evening Shift An electron with speed v and a photon with speed c have the same de-Broglie wavelength. If the kinetic energy and moment... JEE Main 2022 (Online) 26th June Morning Shift A hydrogen atom in its ground state absorbs 10.2 eV of energy. The angular momentum of electron of the hydrogen atom wil... JEE Main 2022 (Online) 27th June Morning Shift An$$\alpha$$particle and a carbon 12 atom has same kinetic energy K. The ratio of their de-Broglie wavelengths$$({\la...
JEE Main 2022 (Online) 27th June Morning Shift
Match List-I with List-II : .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:so...
JEE Main 2022 (Online) 27th June Morning Shift
The de Broglie wavelengths for an electron and a photon are $$\lambda$$e and $$\lambda$$p respectively. For the same kin...
JEE Main 2022 (Online) 28th June Morning Shift
Following statements related to radioactivity are given below : (A) Radioactivity is a random and spontaneous process an...
JEE Main 2022 (Online) 28th June Evening Shift
Let K1 and K2 be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength $$\l... JEE Main 2022 (Online) 28th June Evening Shift In the following nuclear reaction,$$D\buildrel \alpha \over \longrightarrow {D_1}\buildrel {{\beta ^ - }} \over \lon...
JEE Main 2022 (Online) 29th June Evening Shift
The activity of a radioactive material is 2.56 $$\times$$ 10$$-$$3 Ci. If the half life of the material is 5 days, after...
JEE Main 2022 (Online) 29th June Morning Shift
A moving proton and electron have the same de-Broglie wavelength. If K and P denote the K.E. and momentum respectively. ...
JEE Main 2021 (Online) 31st August Morning Shift
A sample of a radioactive nucleus A disintegrates to another radioactive nucleus B, which in turn disintegrates to some ...
JEE Main 2021 (Online) 31st August Morning Shift
There are 1010 radioactive nuclei in a given radioactive element, its half-life time is 1 minute. How many nuclei will r...
JEE Main 2021 (Online) 27th August Morning Shift
At time t = 0, a material is composed of two radioactive atoms A and B, where NA(0) = 2NB(0). The decay constant of both...
JEE Main 2021 (Online) 26th August Evening Shift
A particular hydrogen like ion emits radiation of frequency 2.92 $$\times$$ 1015 Hz when it makes transition from n = 3 ...
JEE Main 2021 (Online) 26th August Morning Shift
Consider the following statements :A. Atoms of each element emit characteristics spectrum.B. According to Bohr's Postula...
JEE Main 2021 (Online) 27th July Evening Shift
An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3 eV. T...
JEE Main 2021 (Online) 27th July Evening Shift
An electron moving with speed v and a photon moving with speed c, have same D-Broglie wavelength. The ratio of kinetic e...
JEE Main 2021 (Online) 25th July Evening Shift
A particle of mass 4M at rest disintegrates into two particles of mass M and 3M respectively having non zero velocities....
JEE Main 2021 (Online) 25th July Morning Shift
What should be the order of arrangement of de-Broglie wavelength of electron ($$\lambda$$e), an $$\alpha$$-particle ($$\... JEE Main 2021 (Online) 25th July Morning Shift An electron of mass me and a proton of mass mp are accelerated through the same potential difference. The ratio of the d... JEE Main 2021 (Online) 22th July Evening Shift A nucleus with mass number 184 initially at rest emits an$$\alpha$$-particle. If the Q value of the reaction is 5.5 MeV... JEE Main 2021 (Online) 22th July Evening Shift For a certain radioactive process the graph between In R and t(sec) is obtained as shown in the figure. Then the value o... JEE Main 2021 (Online) 20th July Evening Shift A nucleus of mass M emits$$\gamma$$-ray photon of frequency 'v'. The loss of internal energy by the nucleus is :[Take ... JEE Main 2021 (Online) 20th July Morning Shift A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years res... JEE Main 2021 (Online) 20th July Morning Shift A proton and an$$\alpha$$-particle, having kinetic energies Kp and K$$\alpha$$respectively, enter into a magnetic fiel... JEE Main 2021 (Online) 18th March Evening Shift The decay of a proton to neutron is : JEE Main 2021 (Online) 18th March Evening Shift The speed of electrons in a scanning electron microscope is 1$$\times$$107 ms-1. If the protons having the same speed ... JEE Main 2021 (Online) 18th March Evening Shift A radioactive sample disintegrates via two independent decay processes having half lives$$T_{1/2}^{(1)}$$and$$T_{1/2}...
JEE Main 2021 (Online) 18th March Morning Shift
A particle is travelling 4 time as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to tha...
JEE Main 2021 (Online) 18th March Morning Shift
Imagine that the electron in a hydrogen atom is replaced by a muon ($$\mu$$). The mass of muon particle is 207 times tha...
JEE Main 2021 (Online) 18th March Morning Shift
The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying...
JEE Main 2021 (Online) 17th March Evening Shift
An electron of mass m and a photon have same energy E. The ratio of wavelength of electron to that of photon is : (c bei...
JEE Main 2021 (Online) 17th March Morning Shift
Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?
JEE Main 2021 (Online) 17th March Morning Shift
If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (vn) for the nth orbit is given as :...
JEE Main 2021 (Online) 17th March Morning Shift
The half-life of Au198 is 2.7 days. The activity of 1.50 mg of Au198 if its atomic weight is 198 g mol$$-$$1 is, (Na = 6...
JEE Main 2021 (Online) 16th March Evening Shift
The de-Broglie wavelength associated with an electron and a proton were calculated by accelerating them through same pot...
JEE Main 2021 (Online) 16th March Evening Shift
Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.
JEE Main 2021 (Online) 16th March Evening Shift
A radioactive sample is undergoing $$\alpha$$ decay. At any time t1, its activity is A and another time t2, the activity...
JEE Main 2021 (Online) 26th February Evening Shift
If $$\lambda$$1 and $$\lambda$$2 are the wavelengths of the third member of Lyman and first member of the Paschen series...
JEE Main 2021 (Online) 26th February Morning Shift
An electron of mass me and a proton of mass mp = 1836 me are moving with the same speed. The ratio of their de Broglie w...
JEE Main 2021 (Online) 25th February Evening Shift
Two radioactive substances X and Y originally have N1 and N2 nuclei respectively. Half life of X is half of the half lif...
JEE Main 2021 (Online) 25th February Morning Slot
The de-Broglie wavelength of a proton and $$\alpha$$-particle are equal. The ratio of their velocities is :
JEE Main 2021 (Online) 24th February Evening Slot
In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D an...
JEE Main 2021 (Online) 24th February Morning Slot
Given the masses of various atomic particles mp = 1.0072 u, mn = 1.0087 u, me = 0.000548 u, $${m_{\overline v }}$$ = 0, ...
JEE Main 2020 (Online) 6th September Evening Slot
A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the se...
JEE Main 2020 (Online) 5th September Evening Slot
Activities of three radioactive substances A, B and C are represented by the curves A, B and C, in the figure. Then thei...
JEE Main 2020 (Online) 5th September Morning Slot
Hydrogen ion and singly ionized helium atom are accelerated, from rest, through the same potential difference. The ratio...
JEE Main 2020 (Online) 3rd September Evening Slot
The radius R of a nucleus of mass number A can be estimated by the formula R = (1.3 $$\times$$ 10–15)A1/3 m. It follow...
JEE Main 2020 (Online) 3rd September Evening Slot
In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining a...
JEE Main 2020 (Online) 3rd September Morning Slot
In a hydrogen atom the electron makes a transition from (n + 1)th level to the nth level. If n &gt;&gt; 1, the frequency...
JEE Main 2020 (Online) 2nd September Evening Slot
In a reactor, 2 kg of 92U235 fuel is fully used up in 30 days. The energy released per fission is 200 MeV. Given that th...
JEE Main 2020 (Online) 2nd September Morning Slot
An electron (mass m) with initial velocity $$\overrightarrow v = {v_0}\widehat i + {v_0}\widehat j$$ is in an electric ...
JEE Main 2020 (Online) 8th January Evening Slot
The graph which depicts the results of Rutherford gold foil experiment with $$\alpha$$-particales is : $$\theta$$ : Sc...
JEE Main 2020 (Online) 8th January Morning Slot
When photon of energy 4.0 eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy TA...
JEE Main 2020 (Online) 8th January Morning Slot
The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6 $$\times$$ 10-16 s. The ...
JEE Main 2020 (Online) 7th January Morning Slot
Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively, If initially a sample has equa...
JEE Main 2019 (Online) 12th April Evening Slot
The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to...
JEE Main 2019 (Online) 12th April Evening Slot
An excited He+ ion emits two photons in succession, with wavelengths 108.5 nm and 30.4 nm, in making a transition to gr...
JEE Main 2019 (Online) 12th April Morning Slot
In Li+ +, electron in first Bohr orbit is excited to a level by a radiation of wavelength $$\lambda$$. When the ion get...
JEE Main 2019 (Online) 10th April Evening Slot
Two radioactive substances A and B have decay constants 5$$\lambda$$ and $$\lambda$$ respectively. At t = 0, a sample ...
JEE Main 2019 (Online) 10th April Evening Slot
Two radioactive materials A and B have decay constants 10$$\lambda$$ and $$\lambda$$, respectively. It initially they ...
JEE Main 2019 (Online) 10th April Morning Slot
A He+ ion is in its first excited state. Its ionization energy is :-
JEE Main 2019 (Online) 9th April Evening Slot
Taking the wavelength of first Balmer line in hydrogen spectrum (n = 3 to n = 2) as 660 nm, the wavelength of the 2nd Ba...
JEE Main 2019 (Online) 9th April Morning Slot
The ratio of mass densities of nuclei of 40Ca and 16O is close to :-
JEE Main 2019 (Online) 8th April Evening Slot
Radiation coming from transitions n = 2 to n = 1 of hydrogen atoms fall on He+ ions in n = 1 and n = 2 states. The possi...
JEE Main 2019 (Online) 8th April Morning Slot
In a radioactive decay chain, the initial nucleus is $${}_{90}^{232}$$Th. At the end there are 6 $$\alpha$$-particles a...
JEE Main 2019 (Online) 12th January Evening Slot
A particle of mass m moves in a circular orbit in a central potential field U(r) = $${1 \over 2}$$ kr2. If Bohr 's quant...
JEE Main 2019 (Online) 12th January Morning Slot
In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is ...
JEE Main 2019 (Online) 11th January Evening Slot
A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength 980$$\mathop A\limits^ \ci... JEE Main 2019 (Online) 11th January Morning Slot Consider the nuclear fission Ne20$$ \to $$&nbsp;2He4 + C12 Given that the binding energy/ nucleon of Ne20, He4 and C12... JEE Main 2019 (Online) 10th January Evening Slot Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 it was 1600 ... JEE Main 2019 (Online) 10th January Morning Slot At a given instant, say t = 0, two radioactive substance A and B have equal activities. the ratio$${{{R_B}} \over {{R_...
JEE Main 2019 (Online) 9th January Evening Slot
A sample of radioactive material A, that has an activity of 10 mCi(1 Ci = 3.7 $$\times$$ 1010 decays/s), has twice the...
JEE Main 2019 (Online) 9th January Morning Slot
At some instant, a radioactive sample S1 having an activity 5 $$\mu$$Ci has twice the number of nuclei as another samp...
JEE Main 2018 (Online) 16th April Morning Slot
Both the nucleus and the atom of some element arein their respective first excited states. They get de-excted by emittin...
JEE Main 2018 (Online) 16th April Morning Slot
Muon ($$\mu$$$$-$$) is a negatively charged (|q| = |e|) particle with a mass m$$\mu$$ = 200 me, where me is the mass o...
JEE Main 2018 (Online) 15th April Evening Slot
An unstable heavy nucleus at rest breaks into two nuclei which move away with velocities in the ratio of 8 : 27. The rat...
JEE Main 2018 (Online) 15th April Evening Slot
A solution containing active cobalt $${{60} \over {27}}Co$$ having activity of $$0.8$$ $$\mu Ci$$ and decay constant $$\... JEE Main 2018 (Online) 15th April Morning Slot The energy required to remove the electron from a singly ionized Helium atom is$$2.2$$times the energies required to r... JEE Main 2018 (Online) 15th April Morning Slot It is found that if a neutron suffers an elastic collinear collision with deuterium at rest, fractional loss of its ener... JEE Main 2018 (Offline) If the series limit frequency of the Lyman series is$${\nu _L}$$, then the series limit frequency of the Pfund series i... JEE Main 2018 (Offline) An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let$${\lambda _n}$... JEE Main 2018 (Offline) Imagine that a reactor converts all given mass into energy and that it operates at a power level of 109 watt. The mass ... JEE Main 2017 (Online) 9th April Morning Slot The acceleration of an electron in the first orbit of the hydrogen atom (n = 1) is : JEE Main 2017 (Online) 9th April Morning Slot Two deuterons undergo nuclear fusion to form a Helium nucleus. Energy released in this process is : (given binding energ... JEE Main 2017 (Online) 8th April Morning Slot According to Bohr’s theory, the time averaged magnetic field at the centre (i.e. nucleus) of a hydrogen atom due to the ... JEE Main 2017 (Online) 8th April Morning Slot A radioactive nucleus A with a half life T, decays into a nucleus B. At t = 0, there is no nucleus B. At sometime t, the... JEE Main 2017 (Offline) Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths r = $${{\lambda _1}}$$/$${{\lambd... JEE Main 2017 (Offline) A hydrogen atom makes a transition from n = 2 to n = 1 and emits a photon. This photon strikes a doubly ionized lithium ... JEE Main 2016 (Online) 9th April Morning Slot Half-lives of two radioactive elements$$A$$and$$B$$are$$20$$minutes and$$40$$minutes, respectively. Initially, t... JEE Main 2016 (Offline) As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion : JEE Main 2015 (Offline) The radiation corresponding to$$3 \to 2$$transition of hydrogen atom falls on a metal surface to produce photoelectron... JEE Main 2014 (Offline) Hydrogen$$\left( {{}_1{H^1}} \right)$$, Deuterium$$\left( {{}_1{H^2}} \right)$$, singly ionised Helium$${\left( {{}_2... JEE Main 2014 (Offline) In a hydrogen like atom electron make transition from an energy level with quantum number $$n$$ to another with quantum ... JEE Main 2013 (Offline) A diatomic molecule is made of two masses $${m_1}$$ and $${m_2}$$ which are separated by a distance $$r.$$ If we calcula... AIEEE 2012 Assume that a neutron breaks into a proton and an electron. The energy released during this process is : (mass of neutr... AIEEE 2012 Hydrogen atom is excited from ground state to another state with principal quantum number equal to $$4.$$ Then the numbe... AIEEE 2012 The half life of a radioactive substance is $$20$$ minutes. The approximate time interval $$\left( {{t_2} - {t_1}} \righ... AIEEE 2011 Energy required for the electron excitation in$$L{i^{ + + }}$$from the first to the third Bohr orbit is : AIEEE 2011 A radioactive nucleus (initial mass number$$A$$and atomic number$$Z$$emits$$3\,\alpha $$- particles and$$2$$posit... AIEEE 2010 A nucleus of mass$$M+\Delta m$$is at rest and decays into two daughter nuclei of equal mass$${M \over 2}$$each. ... AIEEE 2010 A nucleus of mass$$M+\Delta m$$is at rest and decays into two daughter nuclei of equal mass$${M \over 2}$$each. ... AIEEE 2010 The above is a plot of binding energy per nucleon$${E_b},$$against the nuclear mass$$M;A,B,C,D,E,F$$correspond to ... AIEEE 2009 The transition from the state$$n=4$$to$$n=3$$in a hydrogen like atom result in ultra violet radiation. Infrared rad... AIEEE 2009 Suppose an electron is attracted towards the origin by a force$${k \over r}$$where$$'k'$$is a constant and$$'r'$$i... AIEEE 2008 This question contains Statement- 1 and Statement- 2. Of the four choices given after the statements, choose the one t... AIEEE 2008 Which of the following transitions in hydrogen atoms emit photons of highest frequency ? AIEEE 2007 The half-life period of a ratio-active element$$X$$is same as the mean life time of another ratio-active element$$Y.$...
AIEEE 2007
In gamma ray emission from a nucleus
AIEEE 2007
If $${M_O}$$ is the mass of an oxygen isotope $${}_8{O^{17}}$$ , $${M_p}$$ and $${M_N}$$ are the masses of a proton and ...
AIEEE 2007
The energy spectrum of $$\beta$$-particles [ number $$N(E)$$ as a function of $$\beta$$-energy $$E$$ ] emitted from a ...
AIEEE 2006
The $$'rad'$$ is the correct unit used to report the measurement of
AIEEE 2006
If the binding energy per nucleon in $${}_3^7Li$$ and $${}_2^4He$$ nuclei are $$5.60$$ $$MeV$$ and $$7.06$$ $$MeV$$ resp...
AIEEE 2006
When $${}_3L{i^7}$$ nuclei are bombarded by protons, and the resultant nuclei are $${}_4B{e^8}$$, the emitted particles ...
AIEEE 2006
An alpha nucleus of energy $${1 \over 2}m{v^2}$$ bombards a heavy nuclear target of charge $$Ze$$. Then the distance of ...
AIEEE 2006
The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of...
AIEEE 2005
A nuclear transformation is denoted by $$X\left( {n,\alpha } \right)\matrix{ 7 \cr 3 \cr } Li.$$ Which of th...
AIEEE 2005
The intensity of gamma radiation from a given source is $$L$$. On passing through $$36$$ $$mm$$ of lead, it is reduced t...
AIEEE 2005
Starting with a sample of pure $${}^{66}Cu,{7 \over 8}$$ of it decays into $$Zn$$ in $$15$$ minutes. The corresponding h...
AIEEE 2005
If radius of the $$\matrix{ {27} \cr {13} \cr }$$ $$Al$$ nucleus is estimated to be $$3.6$$ fermi then the ...
AIEEE 2005
A nucleus disintegrated into two nuclear parts which have their velocities in the ratio of $$2:1.$$ The ratio of their n...
AIEEE 2004
The binding energy per nucleon of deuteron $$\left( {{}_1^2\,H} \right)$$ and helium nucleus $$\left( {{}_2^4\,He} \righ... AIEEE 2004 An$$\alpha $$-particle of energy$$5MeV$$is scattered through$${180^ \circ }$$by a fixed uranium nucleus. The d... AIEEE 2004 If the binding energy of the electron in a hydrogen atom is$$13.6eV,$$the energy required to remove the electron from ... AIEEE 2003 Which of the following cannot be emitted by radioactive substances during their decay ? AIEEE 2003 In the nuclear fusion reaction$$${}_1^2H + {}_1^3H \to {}_2^4He + n$$given that the repulsive potential energy betwe... AIEEE 2003 The wavelengths involved in the spectrum of deuterium$$\left( {{}_1^2\,D} \right)$$are slightly different from that of... AIEEE 2003 Which of the following atoms has the lowest ionization potential ? AIEEE 2003 A nucleus with$$Z=92$$emits the following in a sequence:$$$\alpha ,{\beta ^ - },{\beta ^ - },\alpha ,\alpha ,\alpha ...
AIEEE 2003
A radioactive sample at any instant has its disintegration rate $$5000$$ disintegrations per minute. After $$5$$ minutes...
AIEEE 2003
When a $${U^{238}}$$ nucleus originally at rest, decays by emitting an alpha particle having a speed $$'u',$$ the recoil...
AIEEE 2003
Which of the following radiations has the least wavelength ?
AIEEE 2003
If $${N_0}$$ is the original mass of the substance of half-life period $${t_{1/2}} = 5$$ years, then the amount of subst...
AIEEE 2002
At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit $$\eqali... AIEEE 2002 If$$13.6eV$$energy is required to ionize the hydrogen atom, then the energy required to remove an electron from ... AIEEE 2002 ## Numerical More In the hydrogen spectrum,$$\lambda$$be the wavelength of first transition line of Lyman series. The wavelength differe... JEE Main 2022 (Online) 26th July Morning Shift$${x \over {x + 4}}$$is the ratio of energies of photons produced due to transition of an electron of hydrogen atom fro... JEE Main 2022 (Online) 25th July Evening Shift A hydrogen atom in its first excited state absorbs a photon of energy x$$\times$$10$$-$$2 eV and excited to a higher e... JEE Main 2022 (Online) 30th June Morning Shift A sample contains 10$$-$$2 kg each of two substances A and B with half lives 4 s and 8 s respectively. The ratio of thei... JEE Main 2022 (Online) 24th June Evening Shift A beam of monochromatic light is used to excite the electron in Li+ + from the first orbit to the third orbit. The wavel... JEE Main 2022 (Online) 27th June Morning Shift The half life of a radioactive substance is 5 years. After x years a given sample of the radioactive substance gets redu... JEE Main 2022 (Online) 29th June Evening Shift$$\sqrt {{d_1}} $$and$$\sqrt {{d_2}} $$are the impact parameters corresponding to scattering angles 60$$^\circ$$and ... JEE Main 2022 (Online) 29th June Morning Shift X different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with pr... JEE Main 2021 (Online) 27th August Evening Shift A particle of mass 9.1$$\times$$10$$-$$31 kg travels in a medium with a speed of 106 m/s and a photon of a radiation o... JEE Main 2021 (Online) 27th July Morning Shift In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0.5$$\mathop A\limits^o $$. If... JEE Main 2021 (Online) 27th July Morning Shift The nuclear activity of a radioactive element becomes$${\left( {{1 \over 8}} \right)^{th}}$$of its initial value in 30... JEE Main 2021 (Online) 25th July Evening Shift From the given data, the amount of energy required to break the nucleus of aluminium$$_{13}^{27}$$Al is __________ x$$...
JEE Main 2021 (Online) 25th July Evening Shift
A radioactive substance decays to $${\left( {{1 \over {16}}} \right)^{th}}$$ of its initial activity in 80 days. The hal...
JEE Main 2021 (Online) 20th July Evening Shift
A particle of mass m moves in a circular orbit in a central potential field U(r) = U0r4. If Bohr's quantization conditio...
JEE Main 2021 (Online) 17th March Evening Shift
The first spectral lines of H-atom in the Balmer series are given $$\lambda$$1, $$\lambda$$2, $$\lambda$$3 considering t...
JEE Main 2021 (Online) 16th March Morning Shift
The wavelength of an X-ray beam is 10$$\mathop A\limits^o$$. The mass of a fictitious particle having the same energy a...
JEE Main 2021 (Online) 25th February Evening Shift
When radiation of wavelength $$\lambda$$ is used to illuminate a metallic surface, the stopping potential is V. When th...
JEE Main 2020 (Online) 2nd September Morning Slot
The first member of the Balmer series of hydrogen atom has a wavelength of 6561 Å. The wavelength of the second member o...
JEE Main 2020 (Online) 8th January Evening Slot

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