Atoms PYQs Set 11 (PDF)

Set 11 of 14 · Questions 301-330 of 394

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Mere Teacher · Previous Year Questions NEET Physics · Atoms · Set 11 (Q301-330)
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301. $When electron jumps from n = 4 level to n = 1 level, the angular momentum of electron changes by$ (1) $\frac{h}{2 π}$ (2) $\frac{2 h}{2 π}$ (3) $\frac{3 h}{2 π}$ (4) $\frac{4 h}{2 π}$ 302. $Photons with energy 5 eV are incident on a cathode C in a photoelectric cell. The maximum energy of emitted photoelectrons is 2 eV. When photons of energy 6eV are incident on C, no photoelectrons will reach the anode A, if the stopping potential of A relative to C is:$ (1) $-3 V$ (2) $+3 V$ (3) $+4 V$ (4) $-1 V$ 303. $The spectral series of the hydrogen atom that lies in the visible region of the electromagnetic spectrum$ (1) $Paschen$ (2) $Balmer$ (3) $Lyman$ (4) $Brackett$ 304. $A free neutron decays into a proton but a free proton does not decay into neutron. This is because$ (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) $neutron has larger rest mass than proton$ 305. $In a hydrogen like atom, when an electron jumps from the M - shell to the L - shell, the wavelength of emitted radiation is λ . If an electron jumps from N -shell to the L -shell, the wavelength of emitted radiation will be :$ (1) $\frac{16}{25} λ$ (2) $\frac{25}{16} λ$ (3) $\frac{20}{27} λ$ (4) $\frac{27}{20} λ$ 306. $Radiation of wavelength λ, is incident on a photocell. The fastest emitted electron has speed v. If the wavelength is changed to \frac{3 λ}{4}, the speed of the fastest emitted electron will be:$ (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) $> v (\frac{4}{3})^{\frac{1}{2}}$ 307. $Hydrogen atom does not emit X -rays because$ (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) $energy levels in it are far apart.$ 308. $In the nucleus of_{11} Na^{23}, the number of protons, neutrons and electrons are$ (1) $11, 12, 0$ (2) $23, 12, 11$ (3) $12, 11, 0$ (4) $23, 11, 12$ 309. $The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is$ (1) $3$ (2) $4$ (3) $1$ (4) $2$ 310. $α ‐particles, β ‐particles and γ ‐rays are all having same energy. Their penetrating power in a given medium in increasing order will be$ (1) $γ, α, α$ (2) $α, β, γ$ (3) $β, α, γ$ (4) $β, γ, α$ 311. $In hydrogen atom, electron excites from ground state to higher energy state and its orbital velocity is reduced to (\frac{1}{3})^{rd} of its initial value. The radius of the orbit in the ground state is R . The radius of the orbit in that higher energy state is ...$ (1) $2 R$ (2) $3 R$ (3) $27 R$ (4) $9 R$ 312. $The ratio of the energies of the electron in the hydrogen atom in the first and second excited states is$ (1) $9 : 4$ (2) $4 : 1$ (3) $8 : 1$ (4) $1 : 8$ 313. $The activity of a radioactive material is 6.4 x 1 0^{- 4} curie. Its half life is 5 days. The activity will become 5 x 1 0^{- 6} curie after:$ (1) $7 days$ (2) $15 days$ (3) $25 days$ (4) $35 days$ 314. $Light of two different frequencies whose photons have energies 1 eV and 2.5 eV respectively illuminate a metallic surface whose work function is 0.5 eV successively. Ratio of maximum speeds emitted electrons will be:$ (1) $1 : 4$ (2) $1 : 2$ (3) $1 : 1$ (4) $1 : 5$ 315. $Speed of electron in its 1st Bohr's orbit is given by 2.18 \times 10^{6} ms^{- 1} . If the time period of electron in n th orbit is measured as 4.10 femto second, the value of n is$ (1) $1$ (2) $2$ (3) $3$ (4) $4$ 316. $An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let λ_{n}, λ_{g} be the de-Broglie wavelength of the electron in the nth state and the ground state respectively. Let Λ_{n} be the wavelength of the emitted photon in the transition from the nth state to the ground state. For large n, (A, B are constants)$ (1) $Λ_{n} \approx A + \frac{B}{λ _{n}^{2}}$ (2) $Λ_{n} \approx A + B λ_{n}^{2}$ (3) $Λ_{n}^{2} \approx A + B λ_{n}^{2}$ (4) $Λ_{n}^{2} \approx λ$ 317. $The ratio of the shortest wavelength of Balmer series to the shortest wavelength of Lyman series for hydrogen atom is:$ (1) $4 : 1$ (2) $1 : 4$ (3) $2 : 1$ (4) $1 : 2$ 318. $The figure indicates the energy level diagram of an atom and the origin of six spectral lines in emission (e.g., line no. 5 arises from the transition from level B to A). Which of the following spectral lines will occur in the absorption spectrum?$ (1) $4, 5, 6$ (2) $1, 2, 3, 4, 5, 6$ (3) $1, 2, 3$ (4) $1, 4, 6.$ 319. $A nucleus of mass M at rest splits into two parts having masses \frac{M ’}{3} and \frac{2 M ’}{3} (M’ < M). The ratio of de Broglie wavelength of two parts will be:$ (1) $1 : 2$ (2) $2 : 1$ (3) $1 : 1$ (4) $2 : 3$ 320. $The total energy of electron in the ground state of hydrogen atom is - 13.6 eV The kinetic energy of an electron in the first excited state is$ (1) $6.8 eV$ (2) $13.6 eV$ (3) $1.7 eV$ (4) $3.4 eV$ 321. $For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is$ (1) $5 : 27$ (2) $27: 5$ (3) $3: 4$ (4) $5 : 36$ 322. $The diagram shows different transitions across the energy levels for an electron in a certain atom. Among these, which transition represents the emission of a photon with the most energy?$ (1) $(II)$ (2) $(I)$ (3) $(IV)$ (4) $(III)$ 323. $Three energy levels of hydrogen atom and the corresponding wavelength of the emitted radiation due to different electron transition$ (1) $λ_{3} = \frac{λ _{1} λ _{2}}{λ _{1} + λ _{2}}$ (2) $λ_{1} = \frac{λ _{2} λ _{3}}{λ _{2} + λ _{3}}$ (3) $λ_{2} = λ_{1} + λ_{3}$ (4) $λ_{2} = \frac{λ _{1} λ _{3}}{λ _{1} + λ _{3}}$ 324. $Hydrogen atom in ground state is excited by a monochromatic radiation of λ = 975 Å. Number of spectral lines in the resulting spectrum emitted will be:$ (1) $3$ (2) $2$ (3) $6$ (4) $10$ 325. $During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is 2000Å and it becomes 6000Å when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is$ (1) $4000Å$ (2) $2000Å$ (3) $3000Å$ (4) $6000Å$ 326. $Given figure shows few data points in a photo electric effect experiment for a certain metal. The minimum energy for ejection of electron from its surface is (Planck’s constant h = 6.62 \times 1 0^{- 34} J.s)$ (1) $2.59 eV$ (2) $2.27 eV$ (3) $1.93 eV$ (4) $2.10 eV$ 327. $A beam of fast moving alpha particles were directed towards a thin film of gold. The parts A, B and C of the transmitted and reflected beams corresponding to the incident parts A, B and C of the beam are shown in the adjoining diagram. The number of alpha particles in$ (1) $A^{’} will be minimum and in B^{’} minimum$ (2) $C^{’} will be minimum and in B^{’} maximum$ (3) $B^{’} will be minimum and in C^{’} maximum$ (4) $A^{’} will be maximum and in C^{’} minimum$ 328. $An electron bean is acceleration by a potential difference V to hit a metallic target to produce X rays. It produces continuous as well as characteristic X-rays. If λ_{min} is the smallest possible wavelength of X-ray in the spectrum, the variation of log λ_{min} with log V is correctly represented in:$ (1) (2) (3) (4) 329. $An electron (mass m) with an initial velocity v = v_{0} i (v_{0} > 0) is moving in an electric field E = - E_{0} i (E_{0} > 0) where E_{0} is constant. If at t = 0 de Broglie wavelength is λ_{0} = \frac{h}{m v _{0}}, then its de Broglie wavelength after time t is given by$ (1) $λ_{0}$ (2) $λ_{0} (1 + \frac{e E _{0} t}{m v _{0}})$ (3) $λ_{0} t$ (4) $\frac{λ _{0}}{( 1 + \frac{e E _{0} t}{m v _{0}} )}$ 330. $The energy levels of an atom is shown is figure. Which one of these transitions will result in the emission of a photon of wavelength 124.1 nm? Given (h = 6.62 x 1 0^{- 34} Js)$ (1) $B$ (2) $A$ (3) $C$ (4) $D$