ATOMIC STRUCTURE – 1

1) The ratio of r.m.s velocity, average velocity and most probable velocity are in the ratio
a) 1.224 : 1.128 : 1
b) 1 : 1.224 : 1.128
c) 1.128 : 1.224 : 1
d) 1 : 1.128 : 1.224

2) 93.75 % of a radioactive material disintegrates in 400 days. How long will it take to disintegrate 75% of the material?
a) 400 days
b) 300 days
c) 200 days
d) 100 days

3) The t1/2 of a radioactive material is 100 sec. What is its average life?
a) 100 sec
b) 144.3 sec
c) 127 sec
d) 69.3 sec

4) The temperature required for a fusion reaction to take place is
a) 300K
b) 600 K
c) 10 3K
d) 106K

5) C14 is formed in the atmosphere from 7N14 by a reaction which is
a) a, n
b) n,a
c) n,p
d) p,a

6) The radio active material used in the treatment of leukaemia is
a) Co60
b) C14
c) I131
d) P32

7) The percentage of Uranium in enriched uranium used as a fuel is
a) 100%
b) 50%
c) 25%
d) 2-3 %

8) There is no nuclear power plant in India at
a) Narora
b) Kalpakam
c) Kayamkulam
d) Tarapur

9) For lighter nuclides to be stable the neutron-proton ratio must be
a) <1
b) zero
c) 1
d) 1.2

10) The lightest artificially prepared element is
a) C14
b) Tc
c) N14
d) Pm

11) The number of alpha and beta particles formed in the 4n series of radioactive elements is
a) 6,4
b) 6,6
c) 8,6
d) 8,4

12) Which is the end product in the 4n + 2 series of radioactive elements?
a) Pb208
b) Bi209
c) Pb207
d) Pb206

13) Carbon dating method was found out by
a) G.T.Seaborg
b) Irene Curie
c) Willard.F.Libby
d) Anderson

14) The range of nuclear forces is
a) 10-7cm
b) 10-9cm
c) 10-11cm
d) 10-13cm

15) An elementAMZ emits several alpha and beta particles in successive steps to form A-10XZ-32. The number of alpha and beta particles formed
a) 6,8
b) 8,6
c) 8,4
d) 4,8

16) 92U235 absorbs a neutron and splits up to form56Ba140 and 36Kr93. The number of neutrons emitted will be
a) 1
b) 2
c) 3
d) 4

17) The electron affinity for inert gases is likely to be
a) High
b) Small
c) Positive
d) Zero

18) During which of the following processes is energy released?
a)
b)
c)
d)

19) Which of the following has the minimum ionic radius?
a)
b)
c)
d)

20) Electron affinity is maximum for
a) Cl
b) F
c) Br
d) I

21) Which of the following ions forms its highly soluble hydroxide in water ?
a)
b)
c)
d)

22) The is maximum for.
a) Na
b) K
c) Ar
d) Be

23) of an element is invariably higher than because.
a) The size of the cation is smaller than that of its atom
b) It is difficult to remove an electron from a cation
c) The effective nuclear charge is higher for a cation
d) All the above are correct

24) The size of the ionic species in their correct order is
a)
b)
c)
d)

25) A sudden large jump between the values of the second and third ionisation energies of an element would be associated with which of the following electronic configurations?
a)
b)
c)
d)

26) Which of the following elements has the lowest value of ionization energy?
a) Mg
b) Ca
c) Ba
d) Sr

27) If the ionic radii of the are about each, the expected values of the atomic radii of K and of F should be respectively
a)
b)
c)
d)

28) Which configuration represents the atom with the highest second ionization energy?
a)
b)
c)
d)

29) Which of the following has the largest size?
a) Al
b)
c)
d)

30) The element with the most electropositive nature is
a) Cu
b) Cs
c) Cr
d) Br

31)

The correct order of the second ionization potential of carbon, nitrogen, oxygen and fluorine is
a) C>N>O>F
b) O>N>F>C
c) O>F>N>C
d) F>O>N>C

32) Which of the following elements has the highest ionization energy?
a) Carbon
b) Boron
c) Oxygen
d) Nitrogen

33) Which has the largest first ionization energy?
a) Na
b) K
c) Rb
d) Li

34) Which of the following requires the largest amount of energy?
a)
b)
c)
d) All require the same amount of energy.

35) Which of the following is an energy consuming process?
a)
b)
c)
d)

36) Arrange S, P and As in order of decreasing ionisation energy:
a) As>P>S
b) As>S>P
c) P>S>As
d) S>P>As

37) In a period, the element with the least atomic size is a/an
a) Alkali metal
b) Halogen
c) Inert gas
d) Chalcogen

38) The ions which are arranged in the correct order of increasing radii are:
a)
b)
c)
d)

39) Which of the following statements is not correct when an electron is added to the atom of a gaseous element?
a) It changes to an anion
b) Energy is released
c) It always becomes stable
d) Its ratio of nuclear charge/number of electrons decreases.

40) Which of the following statements is not correct?
a) All inert gases have negative values of EA
b) The least electronegative elements in the periodic table are cesium or francium
c) Metals have electronegativities less than 2.0
d) All are correct.

41) Iso-electronic species are those which have the
a) Same size
b) Same ionization energy
c) Same electronic configuration
d) Same nuclear charge

42) Which of the following element is expected to have the highest electron affinity?
a)
b)
c)
d)

43) Which of the following are iso-electronic species?

a) I,II,III
b) II,III,IV
c) I,II,IV
d) II and I.

44) Which of the following is most electronegative?
a) Carbon
b) Silicon
c) Lead
d) Tin

45) Which of the following is iso-electronic as well as having the same structure as that of ?
a)
b)
c)
d)

46) Which of the following elements has the highest value of first ionisation potential?
a) Oxygen
b) Argon
c) Barium
d) Cesium

47) Permanent hardness is caused by
a) Calcium bicarbonate
b) Magnesium bicarbonate
c) Sodium chloride
d) Magnesium sulphate

48) As the number of electrons in the valence shell increases, the electron affinity
a) Decrease
b) Increases
c) First decreases and then increases
d) Changes erratically

49) The electronic configuration of the peroxide ion, may be represented as
a)
b)
c)
d)

50) The oxide of an element with the electronic configuration is
a) Acidic
b) Basic
c) Amphoteric
d) Neutral

51) The Bohr radius of the nth orbit of the hydrogen atom is given by
a) 0.53 A0
b) 0.53 n A0
c) 0.53/n2 A0
d) 0.53 n2 A 0

52) The electron build up in an atom is governed by
a) the Aufbau principle
b) Hund’s rule
c) Pauli’s Exclusion principle
d) all the above principles

53) The elements predicted by Mendeleev under the names eka-aluminium, eka-boron and eka-silicon are
a) B, Ga, Ge
b) Ga, Sc, Ge
c) Ge, Sn, Be
d) Ge, Ga, Si

54) An isotone of  32 Ge 76  is
a)

32 Ge 77

b)

33 As 77

c)

34 Se 77

d)

All of these

55) When the speed of electrons increases, the specific charge
a) Decreases
b) Increases
c) Remains same
d) None of these

56) @ A magnet will cause greatest deflection of
a)

a – rays

b)

b – rays

c)

g – rays

d)

Neutrons

57) The spectra given by the transition of an electron from K to N level is
a) Emission
b) Absorption
c) Continuous
d) X rays

58)

The ratio of the energy of a radiation of wavelength 2000 Ao and that of 4000 Ao is

a) 1/4
b) 4
c) 1/2
d) 2

59) The wave character of the electron was experimentally verified by
a) De Broglie
b) Einstein
c) Germer
d) Schrodinger

60) The ratio of the radii of the first three Bohr orbits is
a) 1: 05: 033
b) 1: 2: 3
c) 1: 4: 9
d) 1: 8: 27

61) Light, a well-known form of energy is treated as a form of matter by saying that it consists of
a) Electrons or wave like matter
b) Photons or bundles of energy
c) Neutrons
d) None of these

62)

If the energy of an electron in H atom is given by the expression, – 1312 / n2 K J mol -1, then the energy required to excite the electron from the ground state to the second orbit is
a) 328 KJ
b) 656 KJ
c) 984 KJ
d) 1312 KJ

63) With an increase in the principal quantum number, the energy difference between adjacent energy levels in the H atom
a) Decreases
b) Increases
c) Remains constant
d) Decreases for a low value of Z and increases for a higher value of Z

64) The region in space around the nucleus of an atom where the probability of finding an electron is maximum is called an
a) Sub-level
b) Orbit
c) Orbital
d) None of these

65) When the electrons revolve in stationary orbits
a) There is no change in energy level
b) They become stationary
c) They are gaining kinetic energy
d) There is an increase in energy

66) As we move away from the nucleus, the energy of the orbit
a) Decreases
b) Increases
c) Remains constant
d) None of these

67) 2p – orbitals have
a)

n = 1, l = 1
b) n = 1, l = 2
c) n = 1, l = 0
d) n = 2, l = 0

68) The instability of a nucleus is due to the
a) High proton-neutron ratio
b) High neutron-proton ratio
c) High proton-electron ratio
d) Low proton-electron ratio

69) When a neutral atom is converted into its cation, there is
a) a decrease in atomic number
b) An increase in atomic number
c) A decrease in size
d) An increase in size

70) The quantum number predicting the size as well as the energy of an atomic orbital is
a) l
b) m
c) n
d) s

71) The chromium atom has a different electronic configuration from what is expected according to the Aufbau principle because
a) Cr is a metal
b) It belongs to the d- block elements
c) the half filled d – orbitals give extra stability
d) None of the above

72) The probability of finding an electron in the nucleus is
a) Maximum for the s – orbital
b) More for the d – orbital
c) Depends on the n – value
d) Zero for all orbitals

73)

The number of unpaired electrons in Ne 2+ (Z = 28) is
a) 0
b) 1
c) 2
d) 3


Answer :

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