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Set 8 of 14 · Questions 211-240 of 394

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Mere Teacher · Previous Year Questions NEET Physics · Atoms · Set 8 (Q211-240)
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211. $The angular momentum of the orbital electron is integral multiple of$ (1) $h$ (2) $2 πh$ (3) $\frac{h}{2 π}$ (4) $3 πh$ 212. $Estimate the approximate volume of aluminium nucleus (A = 27) Use (\frac{R _{0} ≃ 1.0 \times 10 ^{- 15} m}{π = 3})$ (1) $1 \times 10^{- 13} (Å)^{3}$ (2) $1 \times 10^{- 10} (Å)^{3}$ (3) $1 \times 10^{- 15} (Å)^{3}$ (4) $1 \times 10^{- 17} (Å)^{3}$ 213. $The force acting on the electron in hydrogen atom (Bohr' theory) is related to the principal quantum number ' n' as$ (1) $n^{4}$ (2) $n^{- 4}$ (3) $n^{2}$ (4) $n^{- 2}$ 214. $The following statements are given about hydrogen atom.(A) The wavelengths of the spectral lines of Lyman series are greater than the wavelength of the second spectral line of Balmer series.(B) The orbits correspond to circular standing waves in which the circumference of the orbit equals a whole number of wavelengths.$ (1) $A is false, B is true$ (2) $A is true, B is false$ (3) $A is false, B is false$ (4) $A is true, B is true$ 215. $A particle A of mass m and initial velocity v collides with a particle B of mass \frac{m}{2} which is at rest. The collision is head on, and elastic. The ratio of the de-Broglie wavelengths λ_{A} to λ_{B} after the collision is :$ (1) $\frac{λ _{A}}{λ _{B}} = \frac{1}{2}$ (2) $\frac{λ _{A}}{λ _{B}} = \frac{1}{3}$ (3) $\frac{λ _{A}}{λ _{B}} = 2$ (4) $\frac{λ _{A}}{λ _{B}} = \frac{2}{3}$ 216. $Which of the following pair of nuclei are isobars of the element?$ (1) $_{1}^{3} H and_{2}^{3} He$ (2) $_{1}^{2} H and_{1}^{3} H$ (3) $_{80}^{198} Hg and_{79}^{197} Au$ (4) $_{92}^{236} U and_{92}^{238} U$ 217. $Read the following statements: (A) Volume of the nucleus is directly proportional to the mass number. (B) Volume of the nucleus is independent of mass number. (C) Density of the nucleus is directly proportional to the mass number. (D) Density of the nucleus is directly proportional to the cube root of the mass number. (E) Density of the nucleus is independent of the mass number. Choose the correct option from the following options.$ (1) $(A) and (D) only.$ (2) $(A) and (E) only.$ (3) $(B) and (E) only.$ (4) $(A) and (C) only$ 218. $The total energy of an electron in an orbit of hydrogen atom is E. The potential energy of the electron in the same orbit is$ (1) $E$ (2) $\frac{E}{2}$ (3) $2 E$ (4) $3 E$ 219. $An atom_{3}^{8} X is bombarded by shower of fundamental particles and in 10 s this atom absorbed 10 electrons, 10 protons and 9 neutrons. The percentage growth in the surface area of the nucleons is recorded by:$ (1) $250 %$ (2) $150 %$ (3) $900 %$ (4) $125 %$ 220. $A particular hydrogen like ion emits radiation of frequency 2.92 \times 1 0^{15} Hz when it makes transition from n = 3 to n = 1. The frequency in Hz of radiation emitted in transition from n = 2 to n = 1 will be:$ (1) $0.44 \times 1 0^{15}$ (2) $6.57 \times 1 0^{15}$ (3) $4.38 \times 1 0^{15}$ (4) $2.46 \times 1 0^{15}$ 221. $In the following nuclear reaction, D α D_{1} β^{-} D_{2} α D_{3} γ D_{4} Mass number of D is 182 and atomic number is 74. Mass number and atomic number of D_{4} respectively will be _______ .$ (1) $174 and 71$ (2) $174 and 69$ (3) $172 and 69$ (4) $172 and 71$ 222. $An α -particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb / m^{2} . The de Broglie wavelength associated with the particle will be:$ (1) $1Å$ (2) $0.1Å$ (3) $10Å$ (4) $0.01Å$ 223. $If the light from Balmer series of hydrogen is used to eject photoelectrons from a metal then the maximum work-function of the metal can be$ (1) $1.89 eV$ (2) $3.4 eV$ (3) $3.8 eV$ (4) $5.1 eV$ 224. $Binding energy of a certain nucleus is 18 \times 10^{8} J . How much is the difference between total mass of all the nucleons and nuclear mass of the given nucleus:$ (1) $10 μg$ (2) $20 μg$ (3) $0.2 μg$ (4) $2 μg$ 225. $A proton and an α -particle are accelerated from rest to the same energy. The de Broglie wavelength λ_{p} and λ_{α} are in the ratio:$ (1) $2 : 1$ (2) $1 : 1$ (3) $2 : 1$ (4) $4 : 1$ 226. $Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The binding energy per nucleon is found to be practically independent of the atomic number A, for nuclei with mass numbers between 30 and 170. Reason (R): Nuclear force is long range. choose the correct answer from the options given below:$ (1) $(A) is true but (R) is false$ (2) $(A) is false but (R) is true$ (3) $Both (A) and (R) are true and (R) is the correct explanation of (A)$ (4) $Both (A) and (R) are true but (R) is NOT the correct explanation of (A)$ 227. $Using a nuclear counter the count rate of emitted particles from a radioactive source is measured. At t = 0 it was 1600 counts per second and t = 8 seconds it was 100 counts per second. The count rate observed, as counts per second, at t = 6 seconds is close to:$ (1) $150$ (2) $400$ (3) $360$ (4) $200$ 228. $Energy required for the electron excitation in L i^{++} from the first to the third Bohr orbit is :$ (1) $12.1 eV$ (2) $36.3 eV$ (3) $108.8 eV$ (4) $122.4 eV$ 229. $An X - ray tube is operated at 1.24 million volt. The shortest wavelength of the produced photon will be:$ (1) $10^{- 2} nm$ (2) $10^{- 3} nm$ (3) $10^{- 4} nm$ (4) $10^{- 1} nm$ 230. $Consider an electron revolving in a circular orbit of hydrogen atom, whose quantum number is n = 2 . The velocity of the electron in that orbit is$ (1) $1.1 \times 10^{6} m / s$ (2) $2.2 \times 10^{7} m / s$ (3) $4.4 \times 10^{6} m / s$ (4) $2.2 \times 10^{5} m / s$ 231. $If n is the orbit number of the electron in a hydrogen atom, the correct statement among the following is$ (1) $electron energy increases as n increases$ (2) $hydrogen emits infrared rays for the electron transition from n = \infty to n=1$ (3) $electron energy is zero for n = 1$ (4) $electron energy varies as n^{2} .$ 232. $An electron of a hydrogen like atom, having Z = 4, jumps from 4^{t h} energy state to 2^{n d} energy state, The energy released in this process, will be: (Given Rch = 13.6 eV) Where R = Rydberg constant c = Speed of light in vacuum h = Planck's constant$ (1) $13 6 eV$ (2) $10.5 eV$ (3) $3.4 eV$ (4) $40.8 eV$ 233. $Maximum frequency of emission is obtained for the transition$ (1) $n = 2 to n = 1$ (2) $n = 6 to n = 2$ (3) $n = 1 to n = 2$ (4) $n = 2 to n = 6$ 234. $An oil drop of radius 2 mm with a density 3g cm^{- 3} is held stationary under a constant electric field 3.55 \times 10^{5} Vm^{- 1} in the Millikan's oil drop experiment.What is the number of excess electrons that the oil drop will possess? (Consider g = 9.81 m/s²)$ (1) $48.8 \times 10^{11}$ (2) $1.73 \times 10^{10}$ (3) $17.3 \times 10^{10}$ (4) $1.73 \times 10^{12}$ 235. $The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths, \frac{λ _{1}}{λ _{2}}, of the photons emitted in this process is:$ (1) $20/7$ (2) $27/5$ (3) $7/5$ (4) $9/7$ 236. $Rutherford's atomic model could account for$ (1) $stability of atoms$ (2) $origin of spectra$ (3) $the positively charged central core of an atom$ (4) $concept of stationary orbits.$ 237. $In which of the following systems will the radius of the first orbit (n = 1) be minimum?$ (1) $doubly ionized lithium$ (2) $singly ionized helium$ (3) $deuterium atom$ (4) $hydrogen$ 238. $When the light of frequency 2 v_{0} (where v_{0} is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v_{1} . When the frequency of the incident radiation is increased to 5 v_{0}, the maximum velocity of electrons emitted from the same plate is v_{2} . The ratio of v_{1} to v_{2} is:$ (1) $1 : 2$ (2) $2 : 1$ (3) $4 : 1$ (4) $1 : 4$ 239. $The ratio of the density of oxygen nucleus (_{8}^{16} O) and helium nucleus (_{2}^{4} He) is$ (1) $4 : 1$ (2) $8 : 1$ (3) $1 : 1$ (4) $2 : 1$ 240. $Assuming the atom is in the ground state, the expression for the magnetic field at a point nucleus in hydrogen atom due to circular motion of electron is (μ_{0} \to permeability of free space, m \to mass of electron ϵ_{0} \to permittivity of free space, h \to Planck ’ s constant)$ (1) $\frac{μ _{0} e ^{3} π m ^{2}}{8 ϵ _{0}^{2} h ^{4}}$ (2) $\frac{μ _{0} e ^{2} π m ^{4}}{6 ϵ _{0}^{3} h ^{4}}$ (3) $\frac{μ _{0} e ^{7} π m ^{2}}{8 ϵ _{0}^{3} h ^{5}}$ (4) $\frac{μ _{0} e ^{3} π m ^{3}}{6 ϵ _{0}^{3} h ^{3}}$