Atomic Structure Level 1

ATOMIC STRUCTURE EXERCISE # I Q.1 UNSOLVED PROBLEMS The study of cathode rays (i.e. electronic discharge through gases) shows that (A) Alpha particles are heavier than protons (B) All forms of matter contain electrons (C) All nuclei contain protons (D) e/m is constant Q.2 Proton is (A) Nucleus of deuterium (B) Ionised hydrogen molecule (C) Ionised hydrogen atom (D) An -particle Q.3 Which is not deflected by magnetic field (A) Neutron (B) Positron (C) Proton (D) Electron Q.4 According to Dalton’s atomic theory, an atom can – (A) Be created (B) Be destroyed (C) Neither be created nor destroyed (D) None Q.5 Rutherford’s experiment on scattering of alpha particles showed for the first time that atom has (A) Electrons (B) Protons (C) Nucleus (D) Neutrons Q.6  - particles are represented by – (A) Lithium atoms (B) Helium nuclei (C) Hydrogen nucleus (D) None of these Q.7 The energy of electron in first Bohr’s orbit of H-atom is –13.6 eV. What will be its potential energy in n = 4th orbit (A) – 13.6 eV (B) –3.4 eV (C) –0.85 eV (D) –1.70 eV Q.8 The frequency of line is 5.09 x 10 14 sec –1 . nm) will be - [c = 3 (A) 510 nm (C) 589 nm Q.9 The spectrum of He-atom may be considered similar to the spectrum of (A) H (B) Li + (C) Na (D) He+ spectrum of sodium Its wave length (in × 108 m/sec](B) 420 nm (D) 622 nm Q.10 Supposing the energy of fourth shell for hydrogen atom is - 50 a.u. (arbitrary unit). What would be its ionization potential (A) 50 (B) 800 (C) 15.4 (D) 20.8 Q.11 Supposing the ionization energy of hydrogen atom is 640 eV. Point out the main shell having energy equal to – 40 eV - 1 (A) n = 2 (B) n = 3 (C) n = 4 (D) n = 5 Q.12 A 1-kW radio transmitter operates at a frequency of 880 Hz. How many photons per second does it emit (A) 1.71 x 1021 (B) 1.71 x 1033 (C) 6.02 x 1023 (D) 2.85 x 1026 Q.13 On Bohr’s stationary orbits (A) Electrons do not move (B) Electrons move emitting radiations (C) Energy of the electron remains constant (D) Angular momentum of the electron is h/2 Q.14 The value of Bohr radius of hydrogen atom is (A) 0.529x 10–7cm (B) 0.529x 10-8cm -9 (C) 0.529x 10 cm (D) 0.529x 10–10 cm Q.15 On the basis of Bohr’s model, the radius of the 3rd orbit is (A) Equal to the radius of first orbit (B)Three times the radius of first orbit (C) Five times the radius of first orbit (D) Nine time the radius of first orbit Q.16 The correct expression derived for the energy of an electron in the nth energy level is (A) En = 2 2me4 2 2 nh (C) En = – 2 2me2 n2h2 (B) En = – (D) En = – 22me4 nh2 2 2me4 n2h2 Q.17 Ionization energy for hydrogen atom in ergs, Joules and eV respectively is (A) 21.8 x 10–12 , 218 x 10–20 , 13.6 (B) 13.6 x 218 x 10–20, 21.8 x 10–13 (C) 21.8 x 10–20, 13.6 , 21.8 x 10–13 (D) 21.8 x 10–13, 13.6, 21.8 x 10–20 Q.18 The velocity of an electron in the third orbit of hydrogen atom (A) 7.28 x107 cm sec–1 (B) 7.08 x 107 cm sec –1 (C) 7.38 x 107cm sec–1 (D) 7.48 x107cm sec–1 Q.19 The ionization energy of a hydrogen atom is 13.6eV. The energy of the third-lowest electronic level in doubly ionized lithium (Z = 3) is (A) –28.7 eV (B) –54.4 eV (C) –122.4 eV (D) –13.6 eV Q.20 The momentum of a photon with energy 20 eV is(A) 10.66 x 10–27 Kg m sec–1 (B) 10.55 x 10–27 Kg m sec–1 (C) 10.60 x 10–27 Kg m sec–1 (D) 10.80 x 10–27 Kg m sec–1 ATOMIC STRUCTURE Q.21 For ionising an excited hydrogen atom, the energy required in eV will be (A) 3.4 or less (B) More than 13.6 (C) Little less than 13.6 (D) 13.6 Q.22 A gas absorbs a photon of 300 nm and then reem itts two photons. On e ph oton has a wavelength 600 nm. The wavelength of second photon is (A) 300 nm (B) 400 nm (C) 500 nm (D) 600 nm Q.23 The specific charge of a proton is 9.6 x 107C kg–1, then for an -particles it will be (A) 2.4 x 107C kg–1 (B) 4.8 x 107C kg–1 7 –1 (C) 19.2 x 10 C kg (D) 38.4 x 107C kg–1 Q.24 For H– atom, the energy required for the removal of electron from various sub-shells is given as under– The order of the energies would be – (A) E1 > E2 > E3 (B) E3 > E2 > E1 (C) E1 = E2 = E3 (D) None of these Q.25 The wave number of the first line of Balmer series of hydrogen is 15200 cm–1. The wave number of the first Balmer line of Li2+ ion is(A) 15200cm–1 (B) 60800 cm–1 (C) 76000 cm–1 (D) 136800 cm–1 Q.26 The wavelength of the third line of the Balmer series for a hydrogen atom is - 21 (A) 100R H 100 (B) 21 R H (C) 21R H 100R H (D) 100 21 Q.27 Wave number of a spectral line for a given transition is x cm–1 for He+ , then its value for Be3+ for the same transition is (A) 4x cm–1 (B) x cm–1 –1 (C) x/4 cm (D) 2x cm–1 Q.28 A photon was absorbed by a hydrogen atom in its ground state and the electron was promoted to the fifth orbit. When the excited atom returned to its ground state, visible and other quanta were emitted. Other quanta are (A) 2  1 (B) 5  2 (C) 3  1 (D) 4  1 Q.29 Wave-length of the first line of Paschen Series hydrogen spectrum is - (R = 109700 cm–1) (A) 18750 (Å) (B) 2854 (Å) (C) 3452 (Å) (D) 6243 (Å) Q.30 What is the change in the orbit radius when the electron in the hydrogen atom (Bohr model) undergoes the first Paschen transition (A) 4.23 x 10–10 m (B) 0.35 x 10–10 m –10 (C) 3.7 x 10 m (D) 1.587 x 10–10 m Q.31 If the shortest wavelength of H atom in Lyman series is x, then longest wavelength in Balmer series of He+ is 9x 36x x 5x (A) (B) (C) (D) 5 5 4 9 Q.32 Which of the following expressions represents the spectrum of Balmer series(If n is the principal quantum number of higher energy level) R(n  1)(n  1) cm 1 (A) v  n2 R(n  2)(n  2) cm 1 (B) v  4n 2 R(n  2)(n  2) cm 1 (C) v  n2 R(n  1)(n  1) cm 1 (D) v  4n 2 Q.33 The maximum number of electron in a principal shell is (A) 2n (B) 2n2 (C) 2 (D) 2n Q.34 Which of the following statements concerning the four quantum numbers is false (A) n gives idea of the size of an orbital (B)  gives the shape of an orbital (C) m gives the energy of the electron in the orbital (D) s gives the direction of spin of the electron in an orbital Q.35 How many electrons can fit into the orbitals that comprise the 3rd quantum shell n = 3 (A) 2 (B) 8 (C) 18 (D) 32 Q.36 The shape of the orbital is given by (A) Spin quantum number (B) Magnetic quantum number (C) Azimuthal quantum number (D) Principal quantum number Q.37 The set of quantum numbers not applicable for an electron in an atom is – (A) n = 1, l = 1, m = 1, s = + 1/2 (B) n = 1, l = 0, m = 0, s = + 1/2 (C) n = 1, l = 0, m = 0, s = – 1/2 (D) n = 2, l = 0, m = 0, s = + 1/2 Q.38 Maximum numbers of electrons in a subshell is given by (A) (2l + 1) (B) 2(2l+1) (C) (2l+1)2 (D) 2(2l + 1)2 Q.39 The magnetic quantum number for valency electron of sodium atom is (A) 3 (B) 2 (C) 1 (D) Zero Q.40 Which one of the following represents an impossible arrangement – ATOMIC STRUCTURE (A) (B) (C) (D) n 3 4 3 5  2 0 2 3 m –2 0 –3 0 s 1/2 1/2 1/2 1/2 Q.41 The set of quantum number for the 19 th electrons in chromium is (A) n=4, l=0,m=0, s =+1/2 or -1/2 (B) n=3, l=2,m=1,s=+1/2 or -1/2 (C) n=3, l=2 m= -1,s=+1/2 or -1/2 (D) n=4, l=1,m=0,s=+1/2 or -1/2 Q.42 The electronic configuration together with the quantum number of last electron for lithium is 1 (A) 1s22s1 2, 0, 0 + 2 1 1 (B) 1s22s1 2, 0, 0 + or – 2 2 1 2 0 1 (C) 1s 2s 2p 2, 1, 0 ± 2 1 (D) 2s22s1 2,1, 0 ± 2 Q.43 The electronic configuration together with the quantum number of last electron for lithium is 1 (A) 1s2 2s1 2, 0, 0, + 2 1 1 (B) 1s2 2s1 2, 0, 0, + or – 2 2 1 (C) 1s2 2s0 2p1 2, 1, 0, ± 2 1 (D) 2s2 2s1 2, 1, 0, ± 2 Q.44 Four sets of values of quantum numbers (n, l, m and s) are given below. Which set does not provide a permissible solution of the wave equation 1 1 (A) 3, 2, –2, (B) 3, 3, 1, – 2 2 1 1 (C) 3, 2, 1, (D) 3, 1, 1, 2 2 Q.45 In presence of magnetic field d-sub orbit is (A) 5 - Fold degenate (B) 3-Fold degenerate (C) 7-Fold degenerate (D) Non- degenerate Q.46 In which of the following pairs is the probability of finding the electron in xy-plane zero for both orbitals ? (A) 3d yz ,4d x 2 – y 2 (B) 2p , dz 2 Q.48 The maximum probability of finding electron in the dxy orbital is (A) Along the x axis (B) Along the y axis (C) At an angle of 45º from the x and y axis (D) At an angle of 90º from the x and y axis Q.49 An electron has a spin quantum number + 1/2 and a magnetic quantum number –1. It cannot be present in (A) d-Orbital (B) f-Orbital (C) s-Orbital (D) p-Orbital Q.50 If the electronic structure of oxygen atom is written as 1s 2 , 2s 2 it would violate (A) Hund’s rule (B) Paulis exclusion principle (C) Both Hund’s and Pauli’s principles (D) None of these Q.51 The energy of an electron of 2py orbital is (A) Greater than 2px orbital (B) Less than 2pz orbital (C) Equal to 2s orbital (D) Same as that of 2px and 2pz orbitals Q.52 The number of unpaired electrons in carbon atom is (A) 2 (B) 4 (C) 1 (D) 3 Q.53 When 4 d orbital is complete, the newly entering electrons goes in to (A) 5f (B) 5s (C) 5p (D) 6d Orbital Q.54 The above configuration is not correct as it violates (A) Only Hund’s rule (B) Only Pauli’s exclusion principle (C) (n + l) rule (D) (Hund + Pauli) rule Q.55 Which of the following elements is represented by the electronic configuration - z (C) 4dzx, 3pz (D) All of these Q.47 For 4py orbital : There are nodal plane = ........ and azimuthal quantum number  = (A) 1, 0 (B) 0, 1 (C) 1, 1 (D) 2, 1 (A) Nitrogen (C) Oxygen (B) Fluorine (D) Neon ATOMIC STRUCTURE Q.56 The electronic configurations of Cr24 and Cu 29 are abnormal (A) Due to extra stability of exactly half filled and exactly fully filled sub shells (B) Because they belong to d-block (C) Both the above (D) None of the above Q.57 The electronic configuration of chromium (Z = 24) is (A) [Ne]3s23p63d44s2 (B) [Ne] 3s23p63d54s1 2 6 1 2 (C) [Ne]3s 3p 3d 4s (D) [Ne] 3s23p64s24p4 Q.58 The number of d-electrons in Fe2+ (At. no. 26) is not equal to that of the –(A) p-Electrons in Ne (At. No. 10) (B) s-Electrons in Mg (At No. 12) (C) d-Electrons in Fe atom (D) p-Electrons in Cl¯ ion (At. No. 17) Q.59 In an electron mi croscope, electron are accelerated to great velocities. Calculate the wavelength of an electron travelling with a velocity of 7.0 megameters per second . The mass of an electron is 9.1×10 -28 g (A) 1.0 × 10–13m (B) 1.0 × 10–7m (C) 1.0 m (D) 1.0 × 10–10m Q.60 A 200g cricket ball is thrown with a speed of 3.0 x 103 cm sec–1. What will be its de Broglie’s wavelength - [h = 6.6 x 10–27g cm2 sec–1] (A) 1.1 x 10–32 cm (B) 2.2 x 10–32 cm –32 (C) 0.55 x 10 cm (D) 11.0 x 10–32 cm Q.61 Which is the de-Broglie equation (A) h = p (B) h = p–1 –1 (C) h = p (D) h = p +  Q.62 Which of the following has the largest de Broglie wavelength given that all have equal velocity (A) CO2 molecule (B) NH3 molecule (C) Electron (D) Proton Q.63 A ball has a mass of 0.1 kg its velocity is 40 m/s, find out de Broglie wave length (A) 1.66 x 10–34m (B) 2 x 10–34 m –34 (C) 3 x 10 m (D) 4 × 10–34 m Q.64 If the uncertainty of position for an electron is zero, what is the uncertainty of the momentum(A) Zero (B)  (C) h (D) Infinite Q.65 Which of the following is the most correct expression for Heisenberg's uncertainty principle h h (A) x. p  (B) x. p  4 4 h h (C) x. p  (D) x . v = 4 4 Q.66 The Heisenberg uncertainty principle can be applied to (A) A cricket ball (B) A foot ball (C) A jet aeroplane (D) An electron Q.67 Velocity of helium atom at 300 K is 2.40 x 102 meter per sec. What is its wave length (mass number of helium is 4) (A) 0.416 nm (B) 0.83 nm (C) 803 Å (D) 8000Å ATOMIC STRUCTURE ANSWER KEY LEVEL # 1 Q.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. D C A C C B D C B B C B C B D Q.No. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Ans. D A A D A A D B C D B D A A C Q.No. 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Ans. A B B C C C A B D C A B B B A Q.No. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Ans. C C C C A D A C D D A B D B A Q.No. 61 62 63 64 65 66 67 Ans. C B A C D B A