CHAPTER STRUCTURE OF ATOM - Amazon S3 · CHAPTER STRUCTURE OF ATOM 1. The spectrum of He is expected to be similar to that ... 13 (b) (c) (d) Ans: (c) 13. Which of the following species

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CHAPTER

STRUCTURE OF ATOM

1. The spectrum of He is expected to be similar

to that [1988] (a) H (b) Li+ (c) Na (d) He+ Ans: (b) 2. The number of spherical nodes in 3p orbitals are [1988] (a) one (b) three (c) none (d) two Ans: (a) 3. If r is the radius of the first orbit, the radius of nth orbit of H-atom is given by [1988] (a) rn2

(b) rn (c) r/n (d) r2 n2

Ans: (a)

4. Which of the following statements do not

form a part of Bohr’s model of hydrogen atom? [1989] (a) Energy of the electrons in the orbits are quantized (b) The electron in the orbit nearest the nucleus has the lowest energy (c) Electrons revolve in different orbits around the nucleus (d) The position and velocity of the electrons in the orbit cannot be determined simultaneously. Ans: (d) 5. Number of unpaired electrons in N2+ is [1989] (a) 2

(b) 0

(c) 1

(d) 3

Ans: (c)

6. The maximum number of electrons in a

subshell is given by the expression [1989] (a) 4l – 2

(b) 4l + 2

(c) 2l + 2

(d) 2n2

Ans: (b)

7. The total number of electrons that can be

accommodated in all the orbitals having principal quantum number 2 and azimuthal quantum number 1 is [1990] (a) 2

(b) 4

(c) 6

(d) 8

Ans: (c)

8. An ion has 18 electrons in the outermost

shell, it is [1990] (a) Cu+ (b) Th4+ (c) Cs+ (d) K+ Ans: (a) 9. In a given atom no two electrons can have the same values for all the four quantum numbers. This is called [1991] (a) Hund’s Rule (b) Aufbau principle (c) Uncertainty principle (d) Pauli’s Exclusion principle. Ans: (d) 10.

[1991] (a) 2

(b) 6

(c) 0

(d) 14 Ans: (d) 11. The order of filling of electrons in the orbitals of an atom will be [1991] (a) 3d, 4s, 4p, 4d, 5s (b) 4s, 3d, 4p, 5s, 4d (c) 5s, 4p, 3d, 4d, 5s (d) 3d, 4p, 4s, 4d, 5s Ans: (b) 12. The energy of an electron in the n the Bohr orbit of hydrogen atom is [1992]

(a)


13

(b)

(c)

(d)

Ans: (c)

13. Which of the following species has four lone

pairs of electrons? [1993] (a) I (b) O–

(c) Cl– (d) He Ans: (b) 14. If ionization potential for hydrogen atom is 13.6 eV, then ionization potential for He+ will be [1993] (a) 54.4 eV (b) 6.8 eV (c) 13.6 eV (d) 24.5 eV Ans: (a)

15. [1994]

(a) (b) (c) (d) Ans: (b)

16. Which of the following is never true for

cathode rays? [1994] (a) They possess kinetic energy (b) They are electromagnetic waves (c) They produce heat (d) They produce mechanical pressure. Ans: (b) 17. The electron was shown experimentally to have wave properties by [1994] (a) de Broglie (b) Davisson and Germer (c) N. Bohr (d) Schrodinger. Ans: (b)

18. 18 When an electron of charge e and mass

m moves with a velocity v about the nuclear charge Ze is circular orbit of radius r, the

potential energy of the electrons is given by [1994] (a) Ze2/r

(b) -Ze2/r (c) Ze2/2r (d) mv2/r Ans: (b)

19. In the photo-electron emission, the energy

of the emitted electron is [1994] (a) greater than the incident photon (b) same as than of the incident photon (c) smaller than the incident photon (d) proportional to the intensity of incident photon. Ans: (c) 20. If electron has spin quantum number + 1/2 and a magnetic quantum number -1, it cannot be present in [1994] (a) d-orbital (b) f-orbital (c) p-orbital (d) s-orbital. Ans: (d) 21.

[1995]

(a)

(b)

(c)

(d) Ans: (a) 22. Uncertainty in position of an electron (mass = 9.1 × 10–28 g) moving with a velocity of 3 × 104 cm/s accurate upto 0.001% will be (use h/4 π) in uncertainty expression where h = 6.626 ×10–

27 erg-second) [1995] (a) 1.93 cm (b) 3.84 cm (c) 5.76 cm (d) 7.68 cm Ans: (a) 23. The orbitals are called degenerate when [1996] (a) they have the same wave functions (b) they have the same wave functions but different energies


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(c) they have different wave functions but same energy (d) they have the same energy Ans: (d) 24. The momentum of a particle having a de Broglie wavelength of 10–17 metres is (Given h = 6.625 × 10–34 Js) [1996] (a) 3.3125 × 10–7 kg ms– 1

(b) 26.5 × 10–7 kg ms– 1

(c) 6.625 × 10–17 kg ms– 1

(d) 13.25 × 10–17 kg ms–1

Ans: (c)

25. The ion that is isoelectronic with CO is

[1997] (a) CN– (b) O2 +

(c) O2– (d) N2

+

Ans: (a)

26.

[1998] (a) 0.13

(b) 1.06

(c) 4.77

(d) 2.12

Ans: (d)

27. The position of both, an electron and a

helium atom is known within 1.0 nm. Further the momentum of the electron is known within 5.0 × 10–26 kg ms– 1 . The minimum uncertainty in the measurement of the momentum of the helium atom is [1998] (a) 50 kg ms– 1

(b) 80 kg ms– 1

(c) 8.0 × 10–26 kg ms– 1

(d) 5.0 × 10–26 kg ms–1

Ans: (d)

28. According to Bohr’s theory the energy

required for an electron in the Li2+ ion to be emitted from n = 2 state is (given that the ground state ionization energy of hydrogen atom is 13.6 eV) [1999] (a) 61.2 eV (b) 13.6 eV (c) 30.6 eV

(d) 10.2 eV Ans: (c)

29. If the energy of a photon is given as: = 3.03

× 10–19 J then, the wavelength of the photon is:

[2000] (a) 6.56 nm (b) 65.6 nm (c) 656 nm (d) 0.656 nm Ans: (c)

30. Set of isoelectronic species is [2000] (a) N2,CO2,CN-,O (b) N,H2S,CO (c) N2 , CO, CN- , O2+2 (d) Ca,Mg,Cl Ans: (c) 31. The following quantum numbers are possible for how many orbital n = 3, l = 2, m =

+2? [2001] (a) 1

(b) 3 (c) 2

(d) 4

Ans: (a)

32. Which of the following is isoelectronic?

[2002] (a) CO2, NO2 (b) NO2–, CO2 (c) CN–, CO (d) SO2, CO2

Ans: (c)

33. In hydrogen atom, energy of first excited

state is –3.4 eV. Find out KEof the same orbit of

Hydrogen atom [2002] (a) + 3.4 eV (b) + 6.8 eV (c) – 13.6 eV (d) + 13.6 eV Ans: (a) 34. The value of Planck's constant is 6.63 × 10–34 Js. The velocity of light is 3.0 × 108 m s– 1 . Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 × 1015

s–1? [2003] (a) 3 × 107

(b) 2 × 10–25


15

(c) 5 × 10– 18

(d) 4 × 101

Ans: (d)

35. The ions O2–, F–, Na+, Mg2+ and Al3+ are

isoelectronic. Their ionic radii show [2003] (a) Adecrease from O2– to F– and then increase from Na+ to Al3+ (b) Asignificant increase from O2– to Al3+ (c) Asignificant decrease from O2– to Al3+ (d) An increase from O2– to F– and then decrease from Na+ to Al3+

Ans: (c)

36. The frequency of radiation emitted when

the electron falls from n = 4 to n = 1 in a hydrogen atom will be (Given ionization energy of H=2.18 ×10–18 J atom–1 and h = 6.625 × 10–34

Js) [2004]

(a)

(b)

(c)

(d) Ans: (c) 37. The energy of second Bohr orbit of the hydrogen atom is 328 kJmol1; hence the energy

of fourth Bohr orbit would be: [2005] (a) -41 kJmol-1

(b) -82 kJmol-1

(c) -164 kJmol-1

(d) -1312 kJmol-1

Ans: (b)

38. Given: The mass of electron is 9.11 × 10–31

kg Plank constant is 6.626 × 10–34 Js, the uncertainty involved in the measurement of

velocity within a distance of 0.1 A is [2006] (a) 5.79 × 107 ms– 1

(b) 5.79 × 108 ms– 1

(c) 5.79 × 105 ms– 1

(d) 5.79 × 106 ms–1

Ans: (d)

39. The orientation of an atomic orbital is

governed by [2006] (a) Spin quantum number

(b) Magnetic quantum number (c) Principal quantum number (d) Azimuthal quantum number Ans: (b) 40.

[2007] (a) , (ii) , (iii) and (iv) (b) (ii) , (iv) and (c) and (iii) (d) (ii) , (iii) and (iv) Ans: (b) 41. If uncertainty in position and momentum

are equal, then uncertainty in velocity is: [2008]

(a)

(b)

(c)

(d) Ans: (a) 42. The measurement of the electron position if associated with an uncertainty in momentum, which is equal to 1 × 10–18 g cm s–1. The uncertainty in electron velocity is, (mass of an

electron is 9 × 10–28 g) [2008] (a) 1 × 109 cm s– 1

(b) 1 × 106 cm s– 1

(c) 1 × 105 cm s– 1

(d) 1 × 1011 cm s–1 Ans: (a)

43. The energy absorbed by each molecule (A2)

of a substance is 4.4 × 10–19 Jand bond energy per molecule is 4.0 × 10–19 J. The kinetic energy

of the molecule per atom will be: [2009] (a) 2.2 × 10–19 J


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(b) 2.0 × 10–19 J (c) 4.0 × 10–20 J (d) 2.0 × 10–20 J Ans: (d) 44. Maximum number of electrons in a subshell of an atom is determined by the following:

[2009] (a) 2 l + 1

(b) 4 l – 2 (c) 2 n2 (d) 4 l + 2

Ans: (d)

45. Which of the following is not permissible

arrangement of electrons in an atom? [2009] (a) n = 5, l = 3, m = 0, s = + 1/2

(b) n = 3, l = 2, m = – 3, s = – 1/2

(c) n = 3, l = 2, m = – 2, s = – 1/2

(d) n = 4, l = 0, m = 0, s = – 1/2

Ans: (b)

46. According to MOtheory which of the

following lists ranks the nitrogen species in

terms of increasing bond order? [2010]

(a)

(b)

(c)

(d)

Ans: (a)

47. Which one of the following species does not

exist under normal conditions? [2010] (a) Be2+

(b) Be2 (c) B2 (d) Li2

Ans: (b)

48. A 0 .66 kg ball is moving with a speed of 100

m/s. The associated wavelength will be ( h=6.6 ×

10-34 Js) [2011] (a) 1.0 u 10–32m (b) 6.6 u 10–32m (c) 6.6 u 10–34m (d) 1.0 u 10–35m Ans: (d)

49. The total number of atomic orbitals in fourth

energy level of an atom is: [2011] (a) 8

(b) 16

(c) 32

(d) 4

Ans: (b)

50. Which of the following has the minimum

bond length? [2011] (a) O2

+

(b) O2 – (c) O22– (d) O2

Ans: (a)

51.

[2011]

(a)

(b)

(c)

(d) Ans: (b) 52. If n = 6, the correct sequence for filling of

electrons will be:[2011] (a)

(b)

(c)

(d)

Ans: (a) 53. According to the Bohr Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon? [2011 M] [2011] (a) n = 6 to n = 1

(b) n = 5 to n = 4

(c) n = 6 to n = 5

(d) n = 5 to n = 3

Ans: (c)

54. The pairs of species of oxygen and their

magnetic behaviours are noted below. Which of the following presents the correct description?

[2012]

(a)


17

(b)

(c)

(d) Ans: (c) 55. Maximum number of electrons in a subshell

with: l = 3 and n = 4 is: [2012] (a) 14

(b) 16

(c) 10

(d) 12

Ans: (a)

56. The correct set of four quantum numbers

for the valence electron of rubidium atom (Z= 37) is [2012]

(a) 5, 1, + 1/2

(b) 6, 0, 0 +1/2

(c) 5, 0, 0 +1/2

(d) 5, 1, 0 +1/2

Ans: (c)

57. The orbital angular momentum of a p-

electron is given as: [2013]

(a)

(b)

(c)

(d) Ans: (a)

58. The value of Planck’s constant is 6.63 × 10–

34 Js. The speed of light is 3 × 1017 nm s– 1 . Which value is closest to the wavelength in nanometer of a quantum of light with frequency of 6 × 1015

s–1? [2013] (a) 25

(b) 50

(c) 75

(d) 10

Ans: (b)

59. What is the maximum numbers of electrons

that can be associated with the following set of quantum numbers?

n = 3, l = 1 and m = –1 [2013] (a) 6

(b) 4

(c) 2

(d) 10

Ans: (c)

60.

[2013] (a) Larger the value of n, the larger is the orbit radius. (b) Equation can be used to calculate the change in energy when the electron changes orbit. (c) For n = 1, the electron has a more negative energy than it does for n = 6 which mean that the electron is more loosely bound in the smallest allowed orbit. (d) The negative sign in equation simply means that the energy or electron bound to the nucleus is lower than it would be if the electrons were at the infinite distance from the nucleus. Ans: (c) 61.

[2013]

(a)

(b)

(c)

(d) Ans: (b) SOLTIONS 1.

2.


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3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.


19

22.

23.

24.

25.

26.

27.

28.

29.

30.

31.


20

32.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.


21

46. 47.

48.

49.

50. 51.

52.

53.

54.

55.

56.

57.

58.

59.

60. Energy of an electron at infinite distance from the nucleus is zero. As an electron approaches the nucleus, the electronattraction increases and hence the energy of electron decreases and thus becomes negative. Thus as the value of n decreases, i.e. lower the orbit is, more negative is the energy of the electron in it. 61.

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CHAPTER STRUCTURE OF ATOM - Amazon S3 · CHAPTER STRUCTURE OF ATOM 1. The spectrum of He is expected to be similar to that ... 13 (b) (c) (d) Ans: (c) 13. Which of the following species