Atoms and Nuclei — practice questions

111 curated practice questions from Atoms and Nuclei (Physics JEE Advanced, NTA Exams) — 97 hard, 14 medium. Every question includes the final answer free; step-by-step worked solutions with a free account.

• Radioactive element decays to form a stable nuclide, then the rate of decay of reactant ( N d ) will vary with time ( t…
• The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation
• The mass number of He is 4 and that for sulphur is 32. The radius of sulphur nucleus is larger than that of helium, by…
• Molybdenum is used as a target element for production of X –rays because it is
• The mean lives of a radio-active substances are 1620 years and 405 years for α–emission and β–emission respectively…
• Ultraviolet radiations of 6.2 eV falls on an aluminium surface (work function 4.2 eV). The kinetic energy in joules of…
• A metal surface of work function 1.07 eV is irradiated with light of wavelength 332 nm . The retarding potential…
• Mosley’s law relates the frequencies of line X-rays with the following characteristics of the target element
• Assertion : Intensity of X -rays can be controlled by adjusting the filament current and voltage. Reason : The…
• The cathode of a photoelectric cell is changed such that the work function changes from W 1 to W 2 ( W 2 > W 1 ). If…
• Assertion : Penetrating power of X -rays increases with the increasing the wavelength. Reason : The penetrating power…
• Electrons with energy 80 keV are incident on the tungsten target of an X-ray tube. K shell electrons of tungsten have…
• When a metal surface is illuminated by light of wavelengths 400 nm and 250 nm , the maximum velocities of the…
• When a point source of monochromatic light is at a distance of 0.2 m from a photoelectric cell, the cut-off voltage and…
• The kinetic energy of the electron in an orbit of radius r in hydrogen atom is ( e = electronic charge)
• If the binding energy per nucleon in Li 7 and He 4 nuclei are respectively 5.60 MeV and 7.06 MeV , then energy of…
• For production of characteristic K β X- rays, the electron transition is
• The masses of neutron and proton are 1.0087 a.m.u. and 1.0073 a.m.u. respectively. If the neutrons and protons combine…
• In an X-ray tube, electrons emitted from a filament (cathode) carrying current I hit a target (anode) at a distance d…
• The minimum wavelength of X -rays produced by electrons accelerated by a potential difference of volts is equal to
• A radioactive nucleus undergoes a series of decay according to the scheme A A_ 1 A_ 2 A_ 3 A_ 4 If the mass number and…
• Assertion : Photosensitivity of a metal is high if its work function is small. Reason : Work function = hf 0 where f 0…
• A metal block is exposed to beams of X- ray of different wavelength. X -rays of which wavelength penetrate most
• Which of the following transitions in a hydrogen atom emits photon of the highest frequency
• The minimum frequency ν of continuous X -rays is related to the applied potential difference V as
• Assertion : Kinetic energy of photo electrons emitted by a photosensitive surface depends upon the intensity of…
• The work function of metal is 1 eV. Light of wavelength 3000 Å is incident on this metal surface. The velocity of…
• Two identical photo-cathodes receive light of frequencies f 1 and f 2 . If the velocities of the photo electrons (of…
• The intensity of X-rays from a Coolidge tube is plotted against wavelength λ as shown in the figure. The minimum…
• A radioactive sample consists of two distinct species having equal number of atoms initially. The mean life time of one…
• Rutherford’s experiment on scattering of a -particles showed for the first time that the atom has
• Rutherford’s alpha particle scattering experiment eventually led to the conclusion that
• An X- ray tube is operated at 50 kV . The minimum wavelength produced is
• An electron jumps from the 4 th orbit to the 2 nd orbit of hydrogen atom. Given the Rydberg’s constant R = 105 cm –1 …
• Assertion : According to classical theory, the proposed path of an electron in Rutherford atom model will be parabolic…
• The half life of the isotope _ 11 Na ^ 24 is 15 hrs . How much time does it take for 7 8 th of a sample of this isotope…
• The binding energy of deuteron _ 1 ^ 2 H is 1.112 MeV per nucleon and an α–particle _ 2 ^ 4 H has a binding energy of…
• Assertion : Radioactivity of 10 8 undecayed radioactive nuclei of half life of 50 days is equal to that of 1.2 × 10 8…
• The shortest wavelength of X-rays emitted from an X-ray tube depends on
• Photoelectric emission is observed from a metallic surface for frequencies ν 1 and ν 2 of the incident light rays (ν 1…
• Threshold frequency for a metal is 10 15 Hz.Light of λ = 4000 Å falls on its surface. Which of the following statements…
• Assertion : Z X A undergoes 2α–decays. 2β–decays and 2γ–decays and the daughter product is Z–2 Y A–8 . Reason : In…
• If m is mass of electron, v its velocity, r the radius of stationary circular orbit around a nucleus with charge Ze …
• Ionization potential of hydrogen atom is 13.6 V . Hydrogen atoms in the ground state are excited by monochromatic…
• The K_ X- ray emission line of tungsten occurs at λ = 0.021 nm. The energy difference between K and L levels in this…
• Which one of the series of hydrogen spectrum is in the visible region
• A photon of energy 3.4 eV is incident on a metal having work function 2 eV . The maximum K.E. of photo-electrons is…
• In Bohr’s model, the atomic radius of the first orbit is r_ 0 , then the radius of the third orbit is
• In the nuclear fusion reaction _ 1 ^ 2 H + _ 1 ^ 3 H _ 2 ^ 4 H + n , given that the repulsive potential energy between…
• Light of wavelength λ strikes a photo-sensitive surface and electrons are ejected with kinetic energy E . If the…
• The half life of radioactive Radon is 3.8 days . The time at the end of which 1/20 th of the Radon sample will remain…
• The potential difference applied to an X -ray tube is increased. As a result, in the emitted radiation
• Assertion : Between any two given energy levels, the number of absorption transition is always less than number of…
• The half life period of radium is 1600 years. The fraction of a sample of radium that would remain after 6400 years is
• If in hydrogen atom, radius of n th Bohr orbit is r n , frequency of revolution of electron in n th orbit is f n choose…
• Imagine another universe in which the value of planck’s constant is 0.0663 Js, but in which the physical laws and all…
• Imagine another universe in which the value of planck’s constant is 0.0663 Js, but in which the physical laws and all…
• If intensity of incident light is increased in PE then which of the following is true
• When radiation is incident on a photoelectron emitter, the stopping potential is found to be 9 volts. If e/m for the…
• If m , m n and m p are the masses of Z X A nucleus, neutron and proton respectively
• Rutherford’s scattering experiment is related to the size of the
• An energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. The energy (in eV )…
• Which one of the following statements is WRONG in the context of X-rays generated from a X-ray tube?
• The Rutherford α-particle experiment shows that most of the α-particles pass through almost unscattered while some are…
• The binding energies per nucleon for a deuteron and an - particle are x 1 and x 2 respectively. What will be the energy…
• Mosley measured the frequency ( f ) of the characteristic X- rays from many metals of different atomic number (Z) and…
• X -rays and gamma rays are both electromagnetic waves. Which of the following statements is true
• An electron has a mass of 9.1 × 10 –31 kg. It revolves round the nucleus in a circular orbit of radius 0.529 × 10 –10…
• Ratio of the wavelengths of first line of Lyman series and first line of Balmer series is
• Assertion : The ionising power of β–particles is less compared α–particles but their penetrating power is more. Reason…
• The intensity of X-rays from a Coolidge tube is plotted against wavelength as shown in the figure. The minimum…
• If the decay or disintegration constant of a radioactive substance is , then its half life and mean life are…
• Which one of the following is true in photoelectric emission
• In a radioactive substance at t = 0, the number of atoms is 8 × 10 4 . Its half life period is 3 years. The number of…
• As the electron in Bohr orbit of Hydrogen atom passes from state n = 2 to n = 1, the kinetic energy K and potential…
• The ionisation potential of hydrogen atom is 13.6 volt . The energy required to remove an electron in the n = 2 state…
• When a beam of accelerated electrons hits a target, a continuous X-ray spectrum is emitted from the target. Which of…
• The half-life of Bi ^ 210 is 5 days. What time is taken by ( 7 8 )^ th part of the sample to decay
• Work function of lithium and copper are respectively 2.3 eV and 4.0 eV . Which one of the metal will be useful for the…
• If λ Cu is the wavelength of K a X-ray line of copper (atomic number 29) and λ Mo is the wavelength of the K a X-ray…
• The stopping potential V for photoelectric emission from a metal surface is plotted along Y- axis and frequency ν of…
• Assertion : The phenomenon of ­ X -ray production is basically inverse of photoelectric effect. Reason : X -rays are…
• According to Einstein’s photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the…
• If an X–ray tube operates at the voltage of 10kV, find the ratio of the de–Brogle wavelength of the incident electrons…
• The K a X-ray emission line of tungsten occurs at l = 0.021 nm. The energy difference between K and L levels in this…
• What percentage of original radioactive atoms is left after five half lives
• Find the ratio of ionisation energy of Bohr’s hydrogen atom and hydrogen-like lithium atom.
• In the given reaction _ z X^ A _ z+1 Y^ A _ z-1 K^ A-4 _ z-1 K^ A-4 . Radioactive radiations are emitted in the sequence
• A ground-state electron (in a hydrogen atom) absorb a photon of energy 3E 0 . How much kinetic energy does the electron…
• Assuming that all laws of thermodynamics can be applied to a nucleus, the α–decay of a nucleus may be regarded as an
• X-rays are produced in an X-ray tube operating at a given accelerating voltage. The wavelength of the continuous X-rays…
• The plot of the number (N) of decayed atoms versus activity (A) of a radioactive substance is
• The work function of a metal is 4.2 eV , its threshold wavelength will be
• The energy levels of the hydrogen spectrum is shown in figure. There are some transitions A , B , C , D and E …
• For intensity I of a light of wavelength 5000Å the photoelectron saturation current is 0.40 µA and stopping potential…
• A radioactive isotope X with a half–life of 1.37 × 10 9 years decays to Y which is stable. A sample of rock from the…
• The value of stopping potential in the following diagram
• K a wavelength emitted by an atom of atomic number Z = 11 is l . Find the atomic number for an atom that emits K a…
• Statement-1 : If the accelerating potential in an X-ray tube is increased, the wavelengths of the characteristic X-rays…
• The figure shows the variation of photocurrent with anode potential for a photo-sensitive surface for three different…
• The wavelength of the K_ line of characteristic X -ray spectra varies with atomic number approximately
• There are n_ 1 photons of frequency γ 1 in a beam of light. In an equally energetic beam, there are n 2 photons of…
• Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate. Reason …
• Binding energy per nucleon plot against the mass number for stable nuclei is shown in the figure. Which curve is correct
• Assertion : Photoelectric effect demonstrates the wave nature of light. Reason : The number of photoelectrons is…
• When an electron jumps from its ground state to the first excited state, the average value of its potential energy ?
• The momentum of a photon is 3.3 ×10 –29 kg–m/sec. Its frequency will be
• One requires energy E n to remove a nucleon from a nucleus and an energy ‘E e ’ to remove an electron from the orbit of…
• Assertion : Hydrogen atom consists of only one electron but its emission spectrum has many lines. Reason : Only Lyman…
• If λ max is 6563 Å, then wave length of second line for Balmer series will be
• What is the power output of 92 U 235 reactor if it takes 30 days to use up 2kg of fuel and if each fission gives 185…

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