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Set 5 of 16 · Questions 121-150 of 453

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Mere Teacher · Previous Year Questions JEE Main Physics · Atoms · Set 5 (Q121-150)
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121. $Bohr model is applied to a particle of mass ' m' and charge ' q' moving in a plane under the influence of a transverse magnetic field ' B'. The energy of the charged particle in the n^{th} level will be$ (1) $2 nhqB / πm$ (2) $nhqB /2 πm$ (3) $nhqB /4 πm$ (4) $nhqB / πm$ 122. $The minimum frequency of photon required to break a particle of mass 15.348 amu into 4 α particles is____kHz . [mass of He nucleus = 4.002 amu, 1 amu = 1.66 \times 10^{- 27} kg, h = 6.6 \times 10^{- 34} J . s and c = 3 \times 10^{8} m / s]$ (1) $14.94 \times 10^{19}$ (2) $9 \times 10^{20}$ (3) $14.94 \times 10^{20}$ (4) $9 \times 10^{19}$ 123. $The ratio for the speed of the electron in the 3^{r d} orbit of H e^{+} to the speed of the electron in the 3^{r d} orbit of hydrogen atom will be:-$ (1) $1 : 1$ (2) $1 : 2$ (3) $4 : 1$ (4) $2 : 1$ 124. $An electron rotates in a circle around a nucleus having positive charge Ze . Correct relation between total energy (E) of electron to its potential energy (U) is:$ (1) $E = U$ (2) $2 E = U$ (3) $2 E = 3 U$ (4) $E = 2 U$ 125. $The ratio of longest wavelength lines in the Balmer and Paschen series of hydrogen spectrum is$ (1) $\frac{5}{36}$ (2) $\frac{7}{20}$ (3) $\frac{7}{144}$ (4) $\frac{5}{27}$ 126. $According to Bohr’s principle, the relation between principal quantum number (n) and radius of orbit (r) is$ (1) $r \propto \frac{1}{n}$ (2) $r \propto \frac{1}{n ^{2}}$ (3) $r \propto n$ (4) $r \propto n^{2}$ 127. $The volume occupied by an atom is greater than the volume of the nucleus by a factor of about$ (1) $1 0^{1}$ (2) $1 0^{5}$ (3) $1 0^{10}$ (4) $1 0^{15}$ 128. $The energy required to ionize a hydrogen like ion in its ground state is 9Rydbergs. What is the wavelength of the radiation emitted when the electron in this ion jumps from the second excited state to the ground state:$ (1) $24.2 nm$ (2) $6.8 nm$ (3) $35.8 nm$ (4) $11.4 nm$ 129. $In hydrogen spectrum, the shortest and longest wavelengths of Balmer series are λ_{1} and λ_{2} respectively. The Rydberg constant of hydrogen is$ (1) $\frac{1}{λ _{1}} - \frac{9}{λ _{2}}$ (2) $\frac{4}{λ _{1}} - \frac{9}{λ _{2}}$ (3) $\frac{9}{λ _{1}} - \frac{9}{λ _{2}}$ (4) $\frac{9}{λ _{1}} - \frac{4}{λ _{2}}$ 130. $In the hydrogen atom spectrum, let E_{1} and E_{2} are energies for the transition n = 2 \to n = 1 and n = 3 \to n = 2, respectively. The ratio E_{2} / E_{1} is$ (1) $\frac{2}{3}$ (2) $\frac{3}{2}$ (3) $\frac{2}{9}$ (4) $\frac{5}{27}$ 131. $Light emitted during the de excitation of electron from n = 3 to n = 2, when incident on a metal, photoelectrons are just emitted from that metal. In which of the following deexcitations photoelectric effect is not possible?$ (1) $From n = 2 to n = 1$ (2) $From n = 3 to n = 1$ (3) $From n = 5 to n=2$ (4) $From n = 4 to n=3$ 132. $The radius of orbit of an electron and the speed of electron in the ground state of hydrogen atom are 5.5 \times 10^{- 11} m and 4 \times 10^{6} ms^{- 1} respectively. Then, the orbital period of this electron in the first excited state will be\dots\dots\dots$ (1) $6.908 \times 10^{- 16} s$ (2) $9.608 \times 10^{- 16} s$ (3) $7.806 \times 10^{- 16} s$ (4) $8.9068 \times 10^{- 16} s$ 133. $The total energy of an electron in an atom in an orbit is - 3.4 eV Its kinetic and potential energies are, respectively$ (1) $3.4 eV, 3.4 eV$ (2) $- 3.4 eV, - 3.4 eV$ (3) $- 3.4 eV, - 6.8 eV$ (4) $3.4 eV, - 6.8 eV$ 134. $An electron in H-atom makes a transition from n = 3 to n = 1. The recoil momentum of H-atom will be-$ (1) $6.45 \times 1 0^{-27} N s$ (2) $6.8 \times 1 0^{-27} N s$ (3) $6.45 \times 1 0^{-24} N s$ (4) $6.8 \times 1 0^{-24} N s$ 135. $In accordance with the Bohr's model, the quantum number that characterises the Earth's revolution around the Sun in an orbit of radius 1.5 \times 10^{11} m with orbital speed 3 \times 10^{4} m s^{- 1} is [Given: mass of Earth = 6 \times 10^{24} kg]$ (1) $8.57 \times 10^{64}$ (2) $5.98 \times 10^{46}$ (3) $2.57 \times 10^{74}$ (4) $2.57 \times 10^{38}$ 136. $Hydrogen atom in the ground state absorbs Δ E amount of energy. If the orbital angular momentum of the electron is increased by \frac{h}{2 π} (h = Planck's constant), then the magnitude of Δ E is$ (1) $12.09 eV$ (2) $12.75 eV$ (3) $10.2 eV$ (4) $13.6 eV$ 137. $A proton and an α -particle, having kinetic energies K_{p} and K_{α} respectively, enter into a magnetic field atright angles. The ratio of the radii of trajectory of proton to that of α -particle is 2:1. The ratio of K_{p} : K_{α} is:$ (1) $1: 8$ (2) $8: 1$ (3) $1: 4$ (4) $4: 1$ 138. $An electron (mass m ) with initial velocity v = v_{0} i + v_{0} j is in an electric field E = - E_{0} k . If λ_{0} is initial de-Broglie wavelength of electron, its de-Broglie wave length at time t is given by :$ (1) $\frac{λ _{0}}{1 + \frac{e ^{2} E _{0}^{2} t ^{2}}{m ^{2} v _{0}^{2}}}$ (2) $\frac{λ _{0}}{1 + \frac{e ^{2} E ^{2} t ^{2}}{2 m ^{2} v _{0}^{2}}}$ (3) $\frac{λ _{0}}{2 + \frac{e ^{2} E ^{2} t ^{2}}{m ^{2} v _{0}^{2}}}$ (4) $\frac{λ _{0} 2}{1 + \frac{e ^{2} E ^{2} t ^{2}}{m ^{2} v _{0}^{2}}}$ 139. $A monochromatic radiation of wavelength λ is incident on a hydrogen sample in ground state. The sample subsequently emits radiation of six different wavelengths, then the value of λ is [Use ch = 1242 eV - m]$ (1) $80 nm$ (2) $85.5 nm$ (3) $97.4 nm$ (4) $100.2 nm$ 140. $In hydrogen spectrum, the shortest wavelength in the Balmer series is λ . The shortest wavelength in the Brackett series is [NEET 2023]$ (1) $4 λ$ (2) $9 λ$ (3) $16 λ$ (4) $2 λ$ 141. $When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from emitted 0.5 eV to 0.8eV. The work function of the metal is:$ (1) $0.65 eV$ (2) $1.0 eV$ (3) $1.3 eV$ (4) $1.5 eV$ 142. $The total energy of an electron in the n th stationary orbit of the hydrogen atom can be obtained by [NEET 2020]$ (1) $E_{n} = \frac{13.6}{n ^{2}} eV$ (2) $E_{n} = - \frac{13.6}{n ^{2}} eV$ (3) $E_{n} = - \frac{1.36}{n ^{2}} eV$ (4) $E_{n} = - 13.6 \times n^{2} eV$ 143. $Consider an electron in a hydrogen atom, revolving in its second excited state (having radius 4.65 Å). The de-Broglie wavelength of this electron is:$ (1) $3.5 Å$ (2) $6.6 Å$ (3) $12.9 Å$ (4) $9.7 Å$ 144. $Arrange the following in the ascending order of wavelength (λ) : (A) Microwaves (λ_{1}) (B) Ultraviolet rays (λ_{2}) (C) Infrared rays (λ_{3}) (D) X-rays (λ_{4}) Choose the most appropriate answer from the options given below:$ (1) $λ_{4} < λ_{3} < λ_{2} < λ_{1}$ (2) $λ_{3} < λ_{4} < λ_{2} < λ_{1}$ (3) $λ_{4} < λ_{3} < λ_{1} < λ_{2}$ (4) $λ_{4} < λ_{2} < λ_{3} < λ_{1}$ 145. $If the series limit frequency of Balmer series is v_{B}, then the series limit frequency of the Brackett series is$ (1) $\frac{4 v _{B}}{25}$ (2) $\frac{v _{B}}{9}$ (3) $\frac{v _{B}}{4}$ (4) $\frac{9 v _{B}}{4}$ 146. $The radius of a nucleus of mass number 64 is 4.8 fermi. Then the mass number of another nucleus having radius of 4 fermi is \frac{1000}{x}, where x is_____$ 147. $X different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with principal quantum number n = 6? The value of X is$ 148. $The ratio of wavelength of spectral lines H_{α} and H_{β} in the Balmer series is \frac{x}{20} . The value of x is____.$ 149. $The average energy released per fission for the nucleus of_{92}^{235} U is 190 MeV . When all the atoms of 47 g pure_{92}^{235} U undergo fission process, the energy released is α \times 10^{23} MeV . The value of α is____.(Avogadro Number = 6 \times 10^{23} per mole)$ 150. $If 917 Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be Å.$