Atoms PYQs Set 12 (PDF)

Set 12 of 14 · Questions 331-360 of 394

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Mere Teacher · Previous Year Questions NEET Physics · Atoms · Set 12 (Q331-360)
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331. $Hydrogen atom in ground state is excited by a monochromatic radiation of λ = 975 A ˚ . Number of spectral lines in the resulting spectrum emitted will be$ (1) $3$ (2) $2$ (3) $6$ (4) $10$ 332. $An alpha-particle of mass m suffers 1-dimensional elastic collision with a nucleus at rest of unknown mass. it’s scattered directly backwards losing, 64% of its initial kinetic energy. The mass of the nucleus is:$ (1) $3.5 m$ (2) $1.5 m$ (3) $4 m$ (4) $2 m$ 333. $The figure shows the energy level of certain atom. When the electron deexcites from 3 E to E, an electromagnetic wave of wavelength λ is cmitted. What is the wavelength of the electromagnetic wave emitted when the electron de excites from 5 E /3 to E?$ (1) $3 λ$ (2) $2 λ$ (3) $5 λ$ (4) $3 λ /5$ 334. $The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is$ (1) $D$ (2) $A$ (3) $B$ (4) $C$ 335. $Which of the following figure represents the variation of ln (\frac{R}{R _{0}}) with In A (If R = radius of a nucleus and A = its mass number)$ (1) (2) (3) (4) 336. $Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths r = λ_{1} / λ_{2}, is given by :$ (1) $r = \frac{1}{3}$ (2) $r = \frac{4}{3}$ (3) $r = \frac{2}{3}$ (4) $r = \frac{3}{4}$ 337. $Magnetic moment due to the motion of the electron in n th energy state of hydrogen atom is proportional to.....$ (1) $n^{- 2}$ (2) $n$ (3) $n^{2}$ (4) $n^{3}$ 338. $Hydrogen atom from excited state comes to the ground by emitting a photon of wavelength λ . The value of principal quantum number 'n' of the excited state will be: (R: Rydberg constant)$ (1) $\frac{λR}{λ - 1}$ (2) $\frac{λR}{λR - 1}$ (3) $\frac{λ}{λR - 1}$ (4) $\frac{λ R ^{2}}{λR - 1}$ 339. $The radiation corresponding to 3 \to 2 transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of 5 \times 1 0^{- 4} T . Assume that the radius of the largest circular path followed by these electrons is 7mm, the work function of the metal is:(Mass of electron = 9.1 x 10-31kg)$ (1) $1.36eV$ (2) $1.88eV$ (3) $0.16eV$ (4) $0.82eV$ 340. $The ionization energy of the electron in the hydrogen atom in its ground state is 13.6 eV The atoms are excited to higher energy levels to emit radiations of 6 wavelengths. Maximum wavelength of emitted radiation corresponds to the transition between$ (1) $n = 3 to n = 1 states$ (2) $n = 2 to n = 1 states$ (3) $n = 4 to n=3 states$ (4) $n = 3 to n = 2 states$ 341. $Energy levels A, B and C of a certain atom corresponding to increasing values of energy i.e., E_{A} < E_{B} < E_{C} . If λ_{1}, λ_{2} and λ_{3} are wavelengths of radiations corresponding to transitions C to B, B to A and C to A respectively, which of the following relations is correct?$ (1) $λ_{3} = λ_{1} + λ_{2}$ (2) $λ_{3} = \frac{λ _{1} λ _{2}}{λ _{1} + λ _{2}}$ (3) $λ_{1} + λ_{2} + λ_{3} = 0$ (4) $λ_{3}^{2} = λ_{1}^{2} + λ_{2^{2}}$ 342. $An electron, a doubly ionized helium ion (He^{++}) and a proton are having the same kinetic energy. The relation between their respective de-Broglie wavelengths ⋋_{e}, ⋋_{H e^{+}} and ⋋_{p} is$ (1) $λ_{e} > λ_{H e^{++}} > λ_{p}$ (2) $λ_{e} < λ_{p} < λ_{H e^{++}}$ (3) $λ_{e} > λ_{p} > λ_{H e^{++}}$ (4) $λ_{e} < λ_{H e^{++}} = λ_{p}$ 343. $When a certain photosensitive surface is illuminated with monochromatic light of frequency ν, the stopping potential for the photo current is - \frac{V _{0}}{2} . When the surface is illuminated by monochromatic light of frequency \frac{ν}{2}, the stopping potential is - V_{0} . The threshold frequency for photoelectric emission is :$ (1) $\frac{4}{3} ν$ (2) $2 ν$ (3) $\frac{3 ν}{2}$ (4) $\frac{5 ν}{3}$ 344. $X (n, α)_{3}^{7} Li, then X will be$ (1) $_{5}^{10} B$ (2) $_{5}^{9} B$ (3) $_{4}^{11} Be$ (4) $_{2}^{4} He$ 345. $An electron is moving initially with velocity v_{0} i + v_{0} j in uniform electric field E = - E_{0} k . If initial wavelength of electron is λ_{0}, its wavelength at time t is:$ (1) $\frac{⋋ _{0}}{1 + \frac{e ^{2} E _{0}^{2}}{2 m ^{2} v _{0}^{2}} t ^{2}}$ (2) $\frac{⋋ _{0}}{2 + \frac{e ^{2} E _{0}^{2}}{m ^{2} v _{0}^{2}} t ^{2}}$ (3) $\frac{⋋ _{0} m v _{0}}{e E _{0} t}$ (4) $\frac{2 ⋋ _{0} m v _{0}}{e E _{0} t}$ 346. $Given below are two statements: one is labelled as Assertion (a)and the other is labelled as Reason (R). Assertion (A): The density of the copper (_{29}^{64} Cu) nucleus is greater than that of the carbon (_{6}^{12} C) nucleus. Reason (R): The nucleus of mass number A has a radius proportional to A^{1/3} . In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $(A) is correct but (R) is not correct$ (2) $Both (A)and (R) are correct but (R) is not the correct explanation of (A)$ (3) $(A)is not correct but (R) is correct$ (4) $Both (A)and (R) are correct and (R) is the correct explanation of (A)$ 347. $Considering Bohr's atomic model for hydrogen atom: (A) the energy of H atom in ground state is same as energy of He+ion in its first excited state.(B) the energy of H atom in ground state is same as that for Li++ion in its second excited state.(C) the energy of H atom in its ground state is same as that of He+ion for its ground state.(D) the energy of He+ion in its first excited state is same as that for Li++ion in its ground state. Choose the correct answer from the options given below:$ (1) $(A), (B)only$ (2) $(A), (D)only$ (3) $(A), (C)only$ (4) $(B), (D)only$ 348. $Surface of certain metal is first illuminated with light of wavelength λ_{1} = 350 nm and then, by light of wavelength λ_{2} = 540 nm . It is found that the maximum speed of the photo electrons in the two cases differ by a factor of 2 . The work function of the metal (in eV ) is close to : (Energy of photon = \frac{1240}{λ ( in nm )} eV)$ (1) $2.5$ (2) $5.6$ (3) $1.4$ (4) $1.8$ 349. $Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Emission of electrons in photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photoemissive substance. Reason (R): A negative electric potential, which stops the emission of electrons from the surface of a photoemissive substance, varies linearly with frequency of incident radiation. choose the most appropriate answer from the options given below :$ (1) $(A) is false but (R) is true$ (2) $(A) is true but (R) is false$ (3) $Both (A) and (R) are true and (R) is the correct explanation of (A)$ (4) $Both (A) and (R) are true but (R) is not the correct explanation of (A)$ 350. $Solar spectrum is an example for$ (1) $band absorption spectrum$ (2) $line absorption spectrum$ (3) $line emission spectrum$ (4) $continuous emission spectrum.$ 351. $The binding energy for the following nuclear reactions are expressed in MeV ._{2} He^{3} +_{0} n^{1} \to_{2} He^{4} + 20 MeV_{2} He^{4} +_{0} n^{1} \to_{2} He^{5} - 0.9 MeV If X_{3}, X_{4}, X_{5} denote the stability of_{2} He^{3},_{2} He^{4} and_{2} He^{5}, respectively, then the correct order is :$ (1) $X_{4} < X_{5} < X_{3}$ (2) $X_{4} > X_{5} > X_{3}$ (3) $X_{4} > X_{5} < X_{3}$ (4) $X_{4} = X_{5} = X_{3}$ 352. $Frank and Hertz experiment proves that$ (1) $light move in the form of waves as well as particles$ (2) $the electron does not radiate energy, while moving in an orbit$ (3) $the energy states of an atom are quantised$ (4) $the whole of the positive charge of the atom is concentrated in the nucleus$ 353. $1 curie represents$ (1) $3.7 \times 10^{7} disintegrations per second$ (2) $3.7 \times 10^{10} disintegrations per second$ (3) $10^{6} disintegrations per second$ (4) $1 disintegration per second$ 354. $Hydrogen (_{1} H^{1}), Deuterium (_{1} H^{2}), singly ionised Helium (_{2} He^{4})^{+} and doubly ionised lithium (_{3} Li^{6})^{++} all have one electron around the nucleus. Consider an elelctron transition from n = 2 to n = 1 . If the wave lengths of emitted radiation are λ_{1}, λ_{2}, λ_{3}, and λ_{4} respectively then approximately which one of the following is correct?$ (1) $4 λ_{1} = 2 λ_{2} = 2 λ_{3} = λ_{4}$ (2) $λ_{1} = 2 λ_{2} = 2 λ_{3} = λ_{4}$ (3) $λ_{1} = λ_{2} = 4 λ_{3} = 9 λ_{4}$ (4) $λ_{1} = 2 λ_{2} = 3 λ_{3} = 4 λ_{4}$ 355. $For a nucleus_{Z}^{A} X having mass number A and atomic number Z (A) The surface energy per nucleon (b_{s}) = - a_{1} A^{\frac{2}{3}} (B) The Coulomb contribution to the binding energy b_{c} = - a_{2} \frac{Z ( Z - 1 )}{A ^{\frac{4}{3}}} (C) The volume energy b_{v} = a_{3} A (D) Decrease in the binding energy is proportional to surface area. (E) While estimating the surface energy, it is assumed that each nucleon interacts with 12 nucleons. (a_{1}, a_{2} and a_{3} are constants) Choose the most appropriate answer from the options given below:$ (1) $B, C, E only$ (2) $C, D only$ (3) $A, B, C, D only$ (4) $B, C only$ 356. $When photon of energy 4.0 eV strikes the surface of a metal A , the ejected photoelectrons have maximum kinetic energy T_{A} eV and de-Broglie wavelength λ_{A} . The maximum kinetic energy of photoelectrons liberated from another metal B by photon of energy 4.50 eV is T_{B} = (T_{A} - 1.5) eV . If the de-Broglie wavelength of these photoelectrons λ_{B} = 2 λ_{A}, then the work function of metal B is:$ (1) $2 eV$ (2) $3 eV$ (3) $1.5 eV$ (4) $4 eV$ 357. $The energy released in the fusion of 2 kg of hydrogen deep in the sun is E_{H} and the energy released in the fission of 2 kg of^{235} U is E_{U} . The ratio \frac{E _{H}}{E _{U}} is approximately: (Consider the fusion reaction as 4 ∣ H + 2 e^{-} \to_{2}^{4} He + 2 v + 6 γ + 26.7 MeV, energy released in the fission reaction of^{235} U is 200 MeV per fission nucleus and N_{A} = 6.023 \times 10^{23})$ (1) $7.62$ (2) $25.6$ (3) $15.04$ (4) $9.13$ 358. $The Bohr model of atoms$ (1) $Assumes that the angular momentum of electrons is quantized.$ (2) $Uses Einstein’s photoelectric equation.$ (3) $Predicts continuous emission spectra for atoms.$ (4) $Predicts the same emission spectra for all types of atoms.$ 359. $The principle of LASER action involves$ (1) $amplification of particular frequency emitted by the system$ (2) $population inversion$ (3) $stimulated emission$ (4) $all of these.$ 360. $Match the LIST-I with LIST-II List - I A._{0}^{1} n +_{92}^{235} U \to_{54}^{140} Xe +_{38}^{94} Sr + 2_{0}^{1} n B. 2 H_{2} + O_{2} \to 2 H_{2} O C._{1}^{2} H +_{1}^{2} H \to_{2}^{3} He +_{0}^{1} n D._{1}^{1} H +_{1}^{3} H \to_{1}^{2} H +_{1}^{2} H List - II I. Chemical reaction II. Fusion with +ve Q value III. Fission IV. Fusion with -ve Q value Choose the correct answer from the options given below$ (1) $A-II, B-I, C-III, D-IV$ (2) $A-III, B-I, C-II, D-IV$ (3) $A-III, B-I, C-IV, D-II$ (4) $A-II, B-I, C-IV, D-III$