Atomic Structure Level 4

ATOMIC STRUCTURE Q.1 Q.2 SECTION : A An atom has a mass of 0.02 kg & uncertainity in its velocity is 9.218 × 10–6 m/s then uncertainity in position is (h = 6.626 × 10–34 J - s) (A) 2.86 × 10–28 m (B) 2.86 × 10–32 cm (C) 1.5 × 10–27 m (D) 3.9 ×10–10 m Energy of H–atom in the ground state is –13.6 eV , Hence energy in the second excited state is – (A) –6.8 eV (B) –3.4 eV (C) –1.51 eV (D) –4.3 eV Q.3 Unertainty in position of a particle of 25 g in space is 10–5 m. Hence uncertainty in velocity (ms–1) is (Planck’s constant h = 6.6 × 10–34 Js) (A) 2.1 × 10–28 (B) 2.1 × 10–34 (C) 0.5 × 10–34 (D) 5.0 × 20–24 Q.4 The orbital angular momentum for an electron h revolving in an orbit is given by l l  1. . This 2 momentus for an s-electron will be given by h h 1 h (A) (B) 2. (C) + . (D) zero 2 2 2 2 Q.5 In Bohr series of lines of hydrogen spectrum, third line from the red end corresponds to where one of the following inter-orbit jumps of electron for Bohr orbits in an atom of hydrogen. (A) 4  1 (B) 2  5 (C) 3  2 (D) 5  2 Q.6 Q.7 Q.8 The de Broglie wavelength of a tennis ball mass 60 g moving with a velocity of 10 mt. per second is approximately (A) 10–16 metres (B) 10–25 metres (C) 10–33 metres (D) 10–31metres Which of the following sets of quantum numbers is correct for an electron in 4f orbital ? 1 (A) n = 4, l = 3 , m = + 4, s = + 2 1 (B) n = 4, l = 4 , m = – 4, s = – 2 1 (C) n = 4, l = 3 , m = + 1, s = + 2 1 (D) n = 4, l = 3 , m = – 2, s = + 2 Consider the ground state of Cr atom (Z = 24). The numbers of electrons with the azimuthal quantum numbers, l =1 and 2 are, respectively Q.9 (A) 12 and 4 (B) 12 and 5 (C) 16 and 4 (D) 16 and 5 The wavelength of the radiation emitted, when in a hydrogen atom electron falls from infinity to stationary state 1, would be (Rydberg constant = 1.097×107 m–1) (A) 91 nm (B) 192 nm (C) 406 nm (D) 9.1×10–8 nm Q.10 Which one of the following sets of ions represents the collection of isoelectronic species? (A) K+, Ca2+, Sc3+, Cl– (B) Na+, Ca2+, Sc3+, F– (C) K+, Cl–, Mg2+, Sc3+ (D) Na+, Mg2+, Al3+, Cl– (Atomic nos.: F = 9, Cl = 17, Na = 11, Mg = 12, Al = 13, K = 19, Ca = 20 , Sc = 21) Q.11 In a multi-electron atom, which of the following orbitals described by the three quantum members will have the same energy in the absence of magnetic and electric fields ? (a) n = 1, l = 0, m = 0 (b) n = 2, l = 0, m = 0 (c) n = 2, l = 1, m = 1 (d) n = 3, l = 2, m = 1 (e) n = 3, l = 2, m = 0 (A) (b) and (c) (B) (a) and (b) (C) (d) and (e) (D) (c) and (d) Q.12 Of the following sets which one does NOT contain isoelectronic species ? (A) CN–, N2, C22– (B) PO43–, SO42–, ClO4– (C) BO33–, CO32–, NO3– (D) SO32–, CO32–, NO3– Q.13 Accordi ng to Bohr's theory, the angular momentum of an electron in 5th orbit is (A) 1.0 h/ (B) 10 h/ (C) 2.5 h/ (D) 25 h/ Q.14 Uncertainty in the position of an electron (mass = 9.1 × 10–31 kg) moving with a velocity 300 m/s, accurate upto 0.001 %, will be (h = 6.63 × 10–34 Js) (A) 5.76 × 10–2 m (B) 1.92 × 10–2 m (C) 3.84 × 10–2 m (D) 19.2 × 10–2 m Q.15 Which of the following sets of quantum numbers represents the highest energy of an atom? (A) n = 3,  = 1, m = 1, s = +½ (B) n = 3,  = 2, m = 1, s = +½ ATOMIC STRUCTURE (C) n = 4,  = 0, m = 0, s = +½ (D) n = 3,  = 0, m = 0, s = +½ order of increasing energy, from the lowest to highest, as (A) (iv) < (ii) < (iii) < (i) (B) (ii) < (iv) < (i) < (iii) (C) (i) < (iii) < (ii) < (iv) (D) (iii) < (i) < (iv) < (ii) Q.16 The ionization enthalpy of hydrogen atom is 1.312 × 106 J mol–1. The energy required to excite the electron in the atom from n = 1 to n = 2 is Q.7 The first use of quantum theory to explain the structure of atom was made by (A) Heisenberg (B) Bohr (C) Planck (D) Einstein Q.8 For a d-electron, the orbital angular momentum is (A) 6.56 × 105 J mol–1 (B) 7.56 × 105 J mol–1 (C) 9.84 × 105 J mol–1 (D) 8.51 × 105 J mol–1 (A) 6h/2 (C) h/2 SECTION : B Q.1 What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition n = 4 to n = 2 in the He+ spectrum ? (A) n= 4 to n = 1 (B) n = 3 to n = 2 (C) n = 3 to n = 1 (D) n = 2 to n= 1 Q.2 Which of the following is violation of Pauli’s exclusion principle ? (A) (B) (C) Q.4 From the given sets of quantum numbers the one that is inconsistent with the theory is (A) n = 3 ;  = 2 ; m = –3 ; s = +1/2 (B) n = 4 ;  = 3 ; m = 3 ; s = +1/2 (C) n = 2 ;  = 1 ; m = 0 ; s = –1/2 (D) n = 4 ;  = 3 ; m = 2 ; s = +1/2 The orbital angular momentum of an electron in 2s orbital is 1 h (A) + . 2 2 (C) Q.5 Q.6 The energy of an electron in the first Bohr orbit of H atom is –13.6 eV. The possible energy value (s) of the excited state(s) for electrons in Bohr orbits of hydrogen is (are) (A) –3.4 eV (B) –4.2 eV (C) –6.8 eV (D) +6.8 eV Q.10 The energy of the electron in the first orbit of He+ is – 871.6 x 10–20 J. The energy of the electron in the first orbit of hydrogen would be (A) –871.6 x 10–20 J (B) –435.8 x 10–20 J –20 (C) –217.9 x 10 J (D) –108.9 x 10–20 J Q.11 Ground state electronic configuration of nitrogen atom can be represented by (D) Q.3 Q.9 (B) 2 h/2 (D) 2h/2 h 2 (B) zero (D) h 2 . 2 Which of the following has maximum number of unpaired electron ? (A) Mg2+ (B) Ti3+ (C) V3+ (D) Fe2+ The electrons, indentified by quantum number n and , (i) n = 4,  = 1 (ii) n = 4,  = 0 (iii) n = 3,  = 2 (iv) n = 3,  = 1 can be placed in (A) (B) (C) (D) Q.12 The electronic configuration of an element is 1s2 2s2 2p6 3s2 3p6 3d5 4s1. This represents its (A) excited state (B) ground state (C) cationic form (D) anionic form Q.13 The number of nodal planes in a px orbital is (A) one (B) two (C) three (D) zero Q.14 The wavelength associated with a golf ball weighing 200g and moving at a speed of 5 m/h is of the order (A) 10–10m (B) 10–20m –30 (C) 10 m (D) 10–40m ATOMIC STRUCTURE Q.15 The quantum numbers +1/2 and –1/2 for the electron spin represent (A) rotation of the electron in clockwise and anticlockwise direction respectively (B) rotation of the electron in anticlockwise and clockwise direction respectively (C) magnetic moment of the electron pointing up and down respectively (D) two quantum mechanical spin states which have no classical analogue Q.16 Rutherford’s experiment, which estabilished the nuclear model of the atom, used a beam of (A) –particles, which impinged on a metal foil and got absorbed (B) –rays, which impinged on a metal foil and ejected electrons (C) helium atoms, which impinged on a metal foil and got scattered (D) helium nuclei, which impinged on a metal foil and got scattered Q.17 If the nit rogen at om had el ec tron ic configuration 1s, it would have energy lower than that of the normal ground state configuration 1s2 2s2 2p3, because the electrons would be closer to the nucleus. Yet, 1s7 is not observed because it violates. (A) Heisenberg uncertainty principle (B) Hund’s rule (C) Pauli’s exclusion principle (D) Bohr postulates of stationary orbits. Q.18 Identify the least stable among the following :] (A) Li– (B) Be– (C) B– (D) C– Q.19 For which of the following the radius will be same as for hydrogen atom n = 1 (A) He+, n = 2 (C) Be3+, n = 2 (B) Li2+, n =2 (D) Li2+ , n = 3 Q.20 The number of radial nodal surface in 3s and 2p (A) 2, 0 (B) 2, 1 (C) 1 , 0 (D) 0, 2 Q.21 According to Bohr's theory , En = Total energy ; Kn = Kinetic energy Vn = Potential energy rn = Radius of nth orbit Match the following : [IIT-2006] Column I Column II (A) Vn/Kn = ? (P) 0 (B) If radius of nth orbital (Q) –1  Enx , x = ? (C) Angular momentum in (R) –2 lowest orbital 1 y (D) n  Z , y  ? r (S) 1 Q.22 Match the entries in Column-I with the correctly related quantum number(s) in Column-II. Column-I Column-II (A) Orbital angular momentum (P) Principal quantum of the electron in a number (Q) hydrogen-like atomic orbital Azimuthal quantum (B) A hydrogen-like one number electron wave function obeying Pauli principle (C) Shape, size and (R) Magnetic quantum orientation of hydrogen number like atomic orbitals (D) Probability density of (S) Electron spin electron of the nucleus quantum number in hydrogen-like atom ATOMIC STRUCTURE LEVEL # 4 SECTION : A Q.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. A C A D B C C,D B A A C D C B B Q.No. 16 Ans. C SECTION : B Q.No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Ans. D B A B D A B A A C A,D B A C D Q.No. 16 17 18 19 20 Ans. D C B C A 21. A  R; B  Q; C  P; D  S 22. A  Q; B  P,Q,R,S; C  P,Q,R; D  P,Q