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Set 6 of 14 · Questions 151-180 of 394

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Mere Teacher · Previous Year Questions NEET Physics · Atoms · Set 6 (Q151-180)
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151. $The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is [NEET 2018]$ (1) $2 : - 1$ (2) $1 : - 1$ (3) $1 : 1$ (4) $1 : - 2$ 152. $Imagine that the electron in a hydrogen atom is replaced by a muon (μ). The mass of muon particle is 207 times that of an electron and charge is equal to the charge of an electron. The ionization potential of this hydrogen atom will be:$ (1) $13.6 eV$ (2) $2815.2 eV$ (3) $331.2 eV$ (4) $27.2 eV$ 153. $Kinetic energy of the particle is E and it’s De-Broglie wavelength is ⋋ . On increasing it's KE by ∆E, it's new De-Broglie wavelength becomes \frac{⋋}{2} . Then AE is$ (1) $3 E$ (2) $E$ (3) $2 E$ (4) $4 E$ 154. $If a radioactive clement having half-life of 30 min is undergoing beta decay, the fraction of radioactive element remains undecayed after 90 min. will be:$ (1) $\frac{1}{8}$ (2) $\frac{1}{16}$ (3) $\frac{1}{4}$ (4) $\frac{1}{2}$ 155. $The magnetic moment (m_{orb}) of a revolving electron around the nucleus varies with the principal quantum number (n) as$ (1) $m_{orb} \propto n^{2}$ (2) $m_{orb} \propto \frac{1}{n}$ (3) $m_{orb} \propto \frac{1}{n ^{2}}$ (4) $m_{orb} \propto n$ 156. $Consider an electron in the n^{th} orbit of a hydrogen atom in the Bohr model. The circumference of the orbit can be expressed in terms of de Broglie wavelength λ of that electron as$ (1) $(0.529) nλ$ (2) $n λ$ (3) $(13.6) λ$ (4) $nλ$ 157. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range 30 to 170. Reason R: Nuclear force is short ranged In the light of the above statements, choose the correct answer from the options given below$ (1) $A is false but R is true$ (2) $Both A and R are true and R is the correct explanation of A$ (3) $Both A and R are true but R is NOT the correct explanation of A$ (4) $A is true but R is false.$ 158. $The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is [NEET 2017]$ (1) $2$ (2) $1$ (3) $4$ (4) $0.5$ 159. $In the Bohr model an electron of mass m moves in a circular orbit around the proton. Considering the orbiting electron to be a circular current loop, the magnetic moment of the hydrogen atom, when the electron is in nth excited state. (Assume, h = Planck's constant)$ (1) $(\frac{e}{2 m} \frac{n ^{2} h}{2 π})$ (2) $(\frac{e}{m}) \frac{nh}{2 π}$ (3) $(\frac{e}{2 m}) \frac{nh}{2 π}$ (4) $(\frac{e}{m}) \frac{n ^{2} h}{2 π}$ 160. $An electron of stationary hydrogen atom jumps from 4^{th} energy level to ground level. The velocity that the photon acquired as a result of electron transition will be (h = Planck's constant, R = Rydberg's constant, m = mass of photon)$ (1) $\frac{9 Rh}{16 m}$ (2) $\frac{11 hR}{16 m}$ (3) $\frac{13 hR}{16 m}$ (4) $\frac{15 hR}{16 m}$ 161. $In the Rutherford’s alpha scattering experiment, as the impact parameter increases, the scattering angle of the alpha particle$ (1) $remains the same$ (2) $is always 90^{\circ}$ (3) $decreases$ (4) $increases$ 162. $A radioactive nucleus A with a half life T, decays into a nucleus B. At t = 0, there is no nucleus B. At sometime t, the ratio of the number of B to that of A is 0.3. Then, t is given by:$ (1) $t = \frac{T}{log ( 1.3 )}$ (2) $t = \frac{T}{2} \frac{log 2}{log 1 . 3}$ (3) $t = T \frac{log 1.3}{log 2}$ (4) $t = T log (1.3)$ 163. $The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5^{th} excited state of a hydrogen atom is:$ (1) $4$ (2) $\frac{1}{4}$ (3) $\frac{1}{2}$ (4) $1$ 164. $The ratio of minimum wavelengths of Lyman and Balmer series will be$ (1) $5$ (2) $10$ (3) $1.25$ (4) $0.25$ 165. $Ionization potential of hydrogen atom is 13.6 eV Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV According to Bohr’s theory, the spectral lines emitted by hydrogen will be$ (1) $one$ (2) $two$ (3) $three$ (4) $four.$ 166. $When hydrogen atom is in its first excited level, its radius is\dots\dots. of the Bohr radius.$ (1) $twice$ (2) $4 times$ (3) $same$ (4) $half$ 167. $A hydrogen atom in ground state absorbs 10.2 eV of energy. The orbital angular momentum of the electron is increased by$ (1) $3.16 \times 10^{- 34} Js$ (2) $1.05 \times 10^{- 34} Js$ (3) $4.22 \times 10^{- 34} Js$ (4) $2.11 \times 10^{- 34} Js$ 168. $A 200 W sodium street lamp emits yellow light of wavelength 0.6 μ m . Assuming it to be 25 % efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is.$ (1) $1.5 \times 10^{20}$ (2) $6 \times 10^{18}$ (3) $62 \times 10^{20}$ (4) $3 \times 10^{19}$ 169. $The magnetic moment of an electron (e) revolving in an orbit around nucleus with an orbital angular momentum is given by:$ (1) $μ_{L} = \frac{e L}{2 m}$ (2) $μ_{L} = - \frac{e L}{2 m}$ (3) $μ_{L} = - \frac{e L}{m}$ (4) $μ_{L} = \frac{e L}{m}$ 170. $A source S_{1} is producing 10^{15} photons per second of wavelength 5000Å . Another source S_{2} is producing 1.02 \times 10^{15} photons per second of wavelength 5100Å . Then (power of S_{2})/(power of S_{1}) is equal to$ (1) $1.00$ (2) $1.02$ (3) $1.04$ (4) $0.98$ 171. $The angular momentum for the electron in Bohr's orbit is L. If the electron is assumed to revolve in second orbit of hydrogen atom, then the change in angular momentum will be$ (1) $Zero$ (2) $2L$ (3) $L$ (4) $\frac{L}{2}$ 172. $An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function 2.75 eV . If the stopping potential of the photoelectron is 10 V, then the value of n is$ (1) $2$ (2) $3$ (3) $4$ (4) $5$ 173. $As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom/ion:$ (1) $its kinetic energy increases but potential energy and total energy decrease$ (2) $kinetic energy, potential energy and total energy decrease$ (3) $kinetic energy decreases, potential energy increases but total energy remains same$ (4) $kinetic energy and total energy decrease but potential energy increases$ 174. $The half life of a radioactive substance is T. The time taken, for disintegrating (\frac{7}{8})^{th} part of its original mass will be:$ (1) $2T$ (2) $3T$ (3) $T$ (4) $8T$ 175. $An electron in a hydrogen atom undergoes a transition from a higher energy level to a lower energy level. The incorrect statement of the following is$ (1) $Kinetic energy of the electron increases$ (2) $Velocity of the electron increases$ (3) $Angular momentum of the electron remains constant$ (4) $Wavelength of de-Broglie wave associated with the motion of electron decreases$ 176. $A hydrogen like atom has one electron revolving round a stationary nucleus. If the energy required to excite the electron from the 2 nd orbital to 3rd orbit is 47.2 eV, find the atomic number of the given atom.$ (1) $3$ (2) $4$ (3) $5$ (4) $6$ 177. $Atomic weight of Boron is 10.81 and it has two isotopes_{5} B^{10} and_{5} B^{11} . Then the ratio of_{5} B^{10} :_{5} B^{11} in nature would be$ (1) $15 : 16$ (2) $10 : 11$ (3) $19 : 81$ (4) $81 : 19$ 178. $When photon of energy 4.0eV strikes the surface of a metal A, the ejected photoelectrons have maximum kinetic energy T_{A} eV and deBroglie wavelength ⋋_{A} . The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50eV is T_{B} = (T_{A} - 1.5)6V. If the DE Broglie wavelength of these photoelectrons ⋋_{B} = 2 ⋋_{A}, then the work function of metal B is:$ (1) $3 eV$ (2) $1.5 eV$ (3) $4.5 eV$ (4) $4 eV$ 179. $Ratio of longest wave lengths corresponding to Lyman and Blamer series in hydrogen spectrum is:$ (1) $\frac{3}{23}$ (2) $\frac{7}{29}$ (3) $\frac{9}{31}$ (4) $\frac{5}{27}$ 180. $The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is:$ (1) $\frac{1}{8}$ (2) $\frac{1}{4}$ (3) $\frac{7}{8}$ (4) $\frac{3}{4}$