Title 12.ATOMS - Questions.pdf ✅

12.ATOMS (1.)If the wavelength of the first line of the balmer series of hydrogen is 6561Å, the wavelength of the second line of the series should be (a.) 13122 Å (b. ) 3280 Å (c.) 4860 Å (d.) 2187 Å (2.)When a hydrogen atom is bombared, the atom is excited to then n = 4 state. The energy released, when the atom goes from n = 4 state to the ground state is (a.) 1.275 eV (b.) 12.75 eV (c.) 5 eV (d.) 8 eV (3.)The ionization energy of hydrogen atom is 13.6eV. Following Bohr’s theory, the energy corresponding to a transition between 3rd and 4th orbit is (a.) 3.40 eV (b. ) 1.51 eV (c.) 0.85 eV (d. ) 0.66 eV (4.)Assuming fto be frequency of first line in Balmer series, the frequency of the immediate next( ie, second) line is (a.) 0.50 f (b.) 1.35 f (c.) 2.05 f (d.) 2.70 f (5.)Continuous emission spectrum is produced by (a.) Incandescent electric lamp (b.) Mercury vapour lamp (c.) Sodium vapour lamp (d.) Polyatomic substances (6.)Bohr’s atom model assumes (a.) The nucleus is of infinite mass and is at rest (b.) Electrons in a quantized orbit will not radiate energy (c.) Mass of electron remains constant (d.) All the above conditions. (7.)According to Bohr’s atomic model, the relation between principal quantum number(n) and radius of orbit(r) is (a.) r ∝ n 2 (b.) r ∝ 1 n2 (c.) r ∝ 1 n (d.) r ∝ n (8.)Mercury vapour lamp gives (a.) Continuous spectrum (b.) Line spectrum (c.) Band spectrum (d.) Absorption spectrum (9.)Band spectrum is also called (a.) Molecular spectrum (b.) Atomic spectrum (c.) Flash spectrum (d.) Line absorption spectrum (10.)The energy of an electron in nth orbit of the hydrogen atom is given by En = −13.6 n2 eV The energy required to raise an electron from the first orbit to the second orbit will be (a.) 10.2 eV (b.) 12.1 eV (c.) 13.6 eV (d.) 3.4 eV (11.)Suppose an electron is attracted towards the origin by a force k r , where k is constant and r is the distance of the electron from the origin. By applying Bohr model to this system, the radius of the nth orbital of the electron is found to be rn and the kinetic energy of the electron to be Tn.Then which of the following is true? (a.) Tn ∝ 1 n2 , rn ∝ n 2 (b. ) Tn independent of n, rn ∝ n (c.) Tn ∝ 1 n , rn ∝ n (d. ) Tn ∝ 1 n , rn ∝ n 2 (12.)Ionisation potential of hydrogen atom is 13.6 eV. The least energy of photon of Balmer series is (a.) 3.4 eV (b. ) 1.89 eV (c.) 10.2 ev (d. ) 8.5 eV (13.)The required energy to detach one electron from Balmer series of hydrogen spectrum is (a.) 13.6 eV (b.) 10.2 eV (c.) 3.4 eV (d.) −1.5 eV (14.)The angular momentum (L) of an electron moving in a stable orbit around nucleus is (a.) Half integral multiple of h 2π (b.) integral multiple of h (c.) integral multiple of h 2π
(d.) Half integral multiple of h (15.)Ionization energy of He + ion at minimum position is (a.) 13.6 eV (b.) 27.2 eV (c.) 54.4 eV (d.) 68.0 eV (16.)Three photons coming from excited atomic hydrogen sample are observed, their energies are 12.1 eV, 10.2 eV and 1.9 eV. These photons must come from (a.) Single atom (b.) Two atoms (c.) Three atoms (d.) Either two or three atom (17.)As the electron in Bohr orbit of hydrogen atom passes from state n=2 to n=1 , the kinetic energy K and potential energy U change as (a.) K two-fold, U four-fold (b.) K four-fold, U two-fold (c.) K four-fold, U also four-fold (d.) K two-fold, U also two-fold (18.)If the radii of nuclei of 13Al 27 and 30Zn 64 are R1 and R2 respectively, then R1 R2 is equal to (a.) 27 64 (b.) 64 27 (c.) 4 3 (d.) 3 4 (19.)The ratio of minimum wavelength of Lyman and Balmer series will be (a.) 10 (b.) 5 (c.) 0.25 (d.) 1.25 (20.)Hydrogen atom excites energy level from fundamental state to n = 3. Number of spectrum lines, according to Bohr, is (a.) 4 (b.) 3 (c.) 1 (d.) 2 (21.)What is the maximum wavelength of light emitted in Lyman series by hydrogen atom? (a.) 691 nm (b.) 550 nm (c.) 380 nm (d.) 122 nm (22.)In a hydrogen atom, the electron in a given orbit has total energy −1.5 eV. The potential energy is (a.) 1.5 eV (b.) −1.5 eV (c.) 3.0 eV (d. ) − 3.0 eV (23.)An electron is moving in an orbit of a hydrogen atom from which there can be a maximum of six transition. An electron is moving in an orbit of another hydrogen atom from which there can be a maximum of three transition. The ratio of the velocities of the electron in these two orbits is (a.) 1 2 (b.) 2 1 (c.) 5 4 (d.) 3 4 (24.)The wave number of the energy emitted when electron comes from fourth orbit to second orbit in hydrogen is 20,397 cm−1 . The wave number of the energy for the same transition in He +is (a.) 5,099 cm−1 (b. ) 20,497 cm−1 (c.) 14400 Å (d. ) 81,588 cm−1 (25.)A neon sign does not produce (a.) A line spectrum (b.) An emission spectrum (c.) An absorption spectrum (d.) Photons (26.)The magnetic moment of the ground state of an atom whose open sub-shell is half-filled with five electrons is (a.) √35√μB (b.) 35 μB (c.) 35√μB (d.) μB√35 (27.)The ratio of minimum to maximum wavelength in Balmer series is (a.) 5: 9 (b. ) 5: 36 (c.) 1: 4 (d. ) 3: 4 (28.)In H spectrum, the wavelength of Hα line is 656 nm whereas in a distance galaxy, the wavelength of Hα line is 706 nm. Estimate the speed of galaxy with respect to earth (a.) 2 × 108ms −1 (b. ) 2 × 107ms −1 (c.) 2 × 106ms −1 (d. ) 2 × 105ms −1 (29.)The acceleration of electron in the first orbit of hydrogen atom is (a.) 4π 2m h3 (b.) h 2 4π2mr
(c.) h 2 2π2m2r 3 (d.) m2h 2 4π2r 3 (30.)The figure indicates the energy levels of a certain atom. When the system moves from 2E level toE, a photon of wavelength λ is emitted. The wavelength of photon produced during its transition from 4E 3 level to E is (a.) λ 3 (b.) 3λ 4 (c.) 4λ 3 (d.) 3λ (31.)The product of linear momentum and angular momentum of an electron of the hydrogen atom is proportional to n x , where x is (a.) 0 (b.) 1 (c.) −2 (d.) 2 (32.)In hydrogen atom, the electron is moving round the nucleus with velocity 2.18 × 106 ms −1 in an orbit of radius 0.528 Å. The acceleration of the electron is (a.) 9 × 1018 ms −2 (b. ) 9 × 1022 ms −2 (c.) 9 × 10−22 ms −2 (d. ) 9 × 1012 ms −2 (33.)The first line of Balmer series has wavelength 6563 Å. What will be the wavelength of the first member of Lyman series? (a.) 1215.4 Å (b. ) 2500 Å (c.) 7500 Å (d. ) 600 Å (34.)The first member of the Balmer’s series of the hydrogen has a wavelength λ, the wavelength of the second member of its series is (a.) 27 20 λ (b.) 20 27 λ (c.) 27 20 λ (d.) None of these (35.)Two energy lavels of an electron in an atom are separated by 2.3 eV. The frequency of radiation emitted when the electrons go from higher to lower level is (a.) 6.95 × 1014 Hz (b.) 3.68 × 1015 Hz (c.) 5.6 × 1014 Hz (d. ) 9.11 × 1015 Hz (36.)Let the potential energy of hydrogen atom in the ground state be regarded as zero. Then its potential energy in the first excited state will be (a.) 20.4 eV (b.) 13.6 eV (c.) 3.4 eV (d.) 10.2eV (37.)The atomic number and the mass number of an atom remains unchanged when it emits (a.) a photon (b.) a neutron (c.) β −particle (d.) An α − particle (38.)The production of band spectra is caused by (a.) Atomic nuclei (b.) Hot metals (c.) Molecules (d.) electrons (39.)For an electron in the second orbit of Bohr’s hydrogen atom, the moment of linear momentum is (a.) nπ (b.) 2πh (c.) 2h π (d.) h π (40.)In a hydrogen atom, the electron moves around the nucleus in a circular orbit of radius 5 × 10−11m. Its time period is 1.5 × 10−16 .The current associated with the electron motion is (charge of electron is 1.6 × 10−16 C) (a.) 1.00 A (b.) 1.066 × 10−3 A (c.) 1.81 × 10−3 A (d. ) 1.66 × 10−3 A (41.)If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li 2+ is (a.) 30.6 eV (b.) 13.6 eV (c.) 3.4 eV (d.) 122.4 eV (42.)The ratio of areas of the electron orbits for the first excited state and the ground state for the hydrogen atom is (a.) 4:1 (b.) 16:1 (c.) 8:1 (d.) 2:1 (43.)Excitation energy of a hydrogen like atom in its first excitation state is 40.8 eV. Energy needed to remove the electron from the ion in ground state is (a.) 40.8 eV (b.) 27.2 eV
(c.) 54.4 eV (d.) 13.6 eV (44.)The radius of hydrogen atom in its ground state is 5.3 × 10−11 m. After collision with an electron it is found to have a radius of 212 × 10−11 m. What is the principal quantum number n of the final state of atom? (a.) n = 4 (b. ) n = 2 (c.) n = 16 (d. ) n = 3 (45.)Energy E of a hydrogen atom with principal quantum number n is given by E = − 13.6 n2 eV.The energy of a photon ejected when the electron jumps from n =3 state to n = 2state of hydrogen , is approximately (a.) 1.5 eV (b.) 0.85 eV (c.) 3.4 eV (d.) 1.9 eV (46.)White light is passed through a dilutee solution of potassium permanganate. The spectrum produced by the emergent light is (a.) Band emission spectrum (b.) Line emission spectrum (c.) Band absorption spectrum (d.) Line absorption spectrum (47.)The total energy of an electron in the first excited state of hydrogen is about −3.4eV. Its kinetic energy in this state is (a.) − 3.4 eV (b.) − 6.8 eV (c.) 6.8 eV (d.) 3.4 eV (48.)The nucleus of an atom consists of (a.) Electrons and protons (b.) Electrons, protons and neutrons (c.) Electrons and Neutrons (d.) Neutrons and protons (49.)Which of the following transition in Balmer series for hydrogen will have longest wavelength? (a.) n=2 to n=1 (b.) n =6 to n=1 (c.) n =3 to n=2 (d.) n =6 to n=2 (50.)The first excited state of hydrogen atoms is 10.2 eV above its ground state. The temperature needed to excite hydrogen atoms to first excited level, is (a.) 7.9 × 104 K (b. ) 3.5 × 104 K (c.) 5.8 × 104K (d. ) 14 × 104 K (51.)The first excitation potential of a given atom is 10.2 V. Then ionisation potential must be (a.) 20.4 V (b.) 13.6 V (c.) 30.6 V (d.) 40.8 V (52.)The binding energy of the electron in the lowest orbit of the hydrogen atom is 13.6 eV. The energies required in eV to remove an electron from the three lowest orbits of the hydrogen atom are (a.) 13.6, 6.8, 8.4 (b.) 13.6, 10.2, 3.4 (c.) 13.6, 27.2, 40.8 (d.) 13.6, 3.4, 1.5 (53.)The series limit wavelength of the Lyman series for the hydrogen atom is given by (a.) 1/R (b. ) 4/R (c.) 9/R (d. ) 16/R (54.)For hydrogen atom electron in n th Bohr orbit, the ratio of radius of orbit to its de-Broglie wavelength is (a.) n 2π (b.) n 2 2π (c.) 1 2πn (d.) 1 2πn2 (55.)The transition from the state n=4 to n=3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from (a.) 2 → 1 (b.) 3 → 2 (c.) 4 → 2 (d.) 5 → 3 (56.)If EPand EK are the potential energy and kinetic energy of the electron in stationary orbit in the hydrogen atom, the value of EP EK is (a.) 2 (b.) −1 (c.) 1 (d.) −2 (57.)The electric potential between a proton and an electron is given by V = V0 In r r0 , where r0 is a constant. Assuming Bohr’s model to be applicable, write variation of rn with n, n being the principal quantum number? (a.) rn ∝ n (b. ) rn ∝ 1 n (c.) rn ∝ n 2