Atoms PYQs Set 12 (PDF)

Set 12 of 16 · Questions 331-360 of 453

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Mere Teacher · Previous Year Questions JEE Main Physics · Atoms · Set 12 (Q331-360)
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331. $The light emitted in the transition n = 3 to n = 2 (where n is the principal quantum number of the state) in hydrogen is called H_{α} -light. Find the maximum work function that a metal can have so that H_{α} -light can emit photoelectrons from it.$ (1) $1.5 eV$ (2) $2.89 eV$ (3) $1.89 eV$ (4) $3.5 eV$ 332. $In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is λ . If an electron jumps from N-shell to eh L-shell, the wavelength of emitted radiation will be:$ (1) $\frac{27}{20} λ$ (2) $\frac{16}{25} λ$ (3) $\frac{25}{16} λ$ (4) $\frac{20}{27} λ$ 333. $The Q-value of a nuclear reaction and kinetic energy of the projectile particle, K_{p} are related as:$ (1) $Q = K_{P}$ (2) $(K_{P} + Q) < 0$ (3) $Q < K_{P}$ (4) $(K_{P} + Q) > 0$ 334. $Continuous emission spectrum is produced by$ (1) $incandescent electric lamp$ (2) $mercury vapour lamp$ (3) $sodium vapour lamp$ (4) $the sun.$ 335. $A photon is emitted in transition from n = 4 to n = l level in hydrogen atom. The corresponding wavelength for this transition is (given, h = 4 x 1 0^{- 15} eVs):$ (1) $94.1 nm$ (2) $941 nm$ (3) $97.4 nm$ (4) $993 nm$ 336. $Frequency of the series limit of Balmer series of hydrogen atom in terms of Rydberg's constant (R) and velocity of light (c) is$ (1) $4 Rc$ (2) $\frac{4}{Rc}$ (3) $Rc$ (4) $\frac{Rc}{4}$ 337. $If the electron in hydrogen atom jumps from second Bohr orbit to ground state and difference between energies of the two states is radiated in the form photons. If the work function of the material is 4.2 eV then stopping potential is [Energy of electron in n^{th} orbit = - \frac{13.6}{n ^{2}} eV]$ (1) $2 eV$ (2) $4 eV$ (3) $6 eV$ (4) $8 eV$ 338. $A radioactive nucleus n_{2} has 3 times the decay constant as compared to the decay constant of another radioactive nucleus n_{1} . If initial number of both nuclei are the same, what is the ratio of number of nuclei of n_{2} to the number of nuclei of n_{1}, after one half-life of n_{1} ?$ (1) $1/8$ (2) $8$ (3) $4$ (4) $1/4$ 339. $If the de-Broglie wavelength of an electron is equal to 10^{- 3} times the wavelength of a photon of frequency 6 \times 10^{14} Hz, then the speed of electron is equal to: (Speed of light = 3 \times 10^{8} m / s, Planck's constant= 6.63 \times 10^{- 34} J . s Mass of electron = 9.1 \times 10^{- 31} kg)$ (1) $1.7 \times 10^{6} m / s$ (2) $1.45 \times 10^{6} m / s$ (3) $1.8 \times 10^{6} m / s$ (4) $1.1 \times 10^{6} m / s$ 340. $The ratio of radii of 3^{rd} and 6^{th} Bohr's orbit in a hydrogen atorn is$ (1) $0.25$ (2) $0.33$ (3) $4$ (4) $3$ 341. $The magnetic filed associated with a light wave is given, at the origin, by B = B_{0} (sin (3.14 \times 10^{7}) ct + sin (6.28 \times 10^{7}) ct) . If this light falls on a sliver pate having a work function of 4.7 eV , what will be the maximum kinetic energy of the photo electrons? (c = 3 \times 10^{8} ms^{- 1}, h = 6.6 \times 10^{- 34} J - s)$ (1) $6.82 eV$ (2) $12.5 eV$ (3) $7.72 eV$ (4) $8.52 eV$ 342. $In L i^{++}, electron in first Bohr orbit is excited to a level by a radiation of wavelength λ . When the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ ? (Given: h = 6.63 \times 10^{- 34} Js; c = 3 \times 10^{8} m s^{- 1})$ (1) $11.4 nm$ (2) $9.4 nm$ (3) $12.3 nm$ (4) $10.80 nm$ 343. $The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly____nm.$ (1) $1550$ (2) $1217$ (3) $1875$ (4) $1784$ 344. $When electron jumps from n = 4 level to n = 1 level, the angular momentum of electron changes by$ (1) $\frac{h}{2 π}$ (2) $\frac{2 h}{2 π}$ (3) $\frac{3 h}{2 π}$ (4) $\frac{4 h}{2 π}$ 345. $Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is:$ (1) $-3 V$ (2) $+3 V$ (3) $+4 V$ (4) $-1 V$ 346. $The spectral series of the hydrogen atom that lies in the visible region of the electromagnetic spectrum$ (1) $Paschen$ (2) $Balmer$ (3) $Lyman$ (4) $Brackett$ 347. $A free neutron decays into a proton but a free proton does not decay into neutron. This is because$ (1) $neutron is an uncharged particle$ (2) $proton is a charged particle$ (3) $neutron is a composite particle made of a proton and an electron$ (4) $neutron has larger rest mass than proton$ 348. $In a hydrogen like atom, when an electron jumps from the M - shell to the L - shell, the wavelength of emitted radiation is λ . If an electron jumps from N -shell to the L -shell, the wavelength of emitted radiation will be :$ (1) $\frac{16}{25} λ$ (2) $\frac{25}{16} λ$ (3) $\frac{20}{27} λ$ (4) $\frac{27}{20} λ$ 349. $Radiation of wavelength λ, is incident on a photocell. The fastest emitted electron has speed v. If the wavelength is changed to \frac{3 λ}{4}, the speed of the fastest emitted electron will be:$ (1) $< v (\frac{4}{3})^{\frac{1}{2}}$ (2) $= v (\frac{4}{3})^{\frac{1}{2}}$ (3) $= v (\frac{3}{4})^{\frac{1}{2}}$ (4) $> v (\frac{4}{3})^{\frac{1}{2}}$ 350. $Hydrogen atom does not emit X -rays because$ (1) $its size is very small$ (2) $energy levels in it are very close to each other$ (3) $it contains only a single electron$ (4) $energy levels in it are far apart.$ 351. $In the nucleus of_{11} Na^{23}, the number of protons, neutrons and electrons are$ (1) $11, 12, 0$ (2) $23, 12, 11$ (3) $12, 11, 0$ (4) $23, 11, 12$ 352. $The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is$ (1) $3$ (2) $4$ (3) $1$ (4) $2$ 353. $α ‐particles, β ‐particles and γ ‐rays are all having same energy. Their penetrating power in a given medium in increasing order will be$ (1) $γ, α, α$ (2) $α, β, γ$ (3) $β, α, γ$ (4) $β, γ, α$ 354. $In hydrogen atom, electron excites from ground state to higher energy state and its orbital velocity is reduced to (\frac{1}{3})^{rd} of its initial value. The radius of the orbit in the ground state is R . The radius of the orbit in that higher energy state is ...$ (1) $2 R$ (2) $3 R$ (3) $27 R$ (4) $9 R$ 355. $A sample contains 10-2 kg each of two substances A and B with half lives 4 s and 8 s respectively. The ratio of then atomic weights is 1 : 2. The ratio of the amounts of A and B after 16 s is \frac{x}{100} . The value of x is_______.$ 356. $In a hydrogen spectrum, λ be the wavelength of first transition line of Lyman series. The wavelength difference will be "a λ " between the wavelength of 3^{r d} transition line of Paschen series and that of 2^{n d} transition line of Balmer Series where a =_______$ 357. $The first three spectral lines of H-atom in the Balmer series are given ⋋_{1}, ⋋_{2}, ⋋_{3} considering the Bohr atomicmodel, the wave lengths of first and third spectral lines (\frac{⋋ _{1}}{⋋ _{3}}) are related by afactor of approximately 'x' \times 10^{- 1} . The value of x,to the nearest integer, is ____.$ 358. $The surface of a metal is illuminated alternately with photons of energies E_{1} = 4eV and E_{2} = 2.5eV respectively. The ratio of maximum speeds of the photoelectrons emitted in the two cases is 2. The work function of the metal in (eV) is$ 359. $If Rydberg's constant is R, the longest wavelength of radiation in Paschen series will be \frac{α}{7 R}, where α = -------$ 360. $The decay constant for a radioactive nuclide is 1.5 \times 10^{- 5} s^{- 1} . Atomic weight of the substance is 60 g mole^{- 1}, N_{A} = 6 \times 10^{23} . The activity of 1.0 μ g of the substance is____\times 10^{10} Bq .$