# M.C.Q : Atomic Structure ( 11 to 20 )

LEVEL – I
11. Electromagnetic radiation (Photon) with least wavelength result when an electron in the hydrogen atom falls from n = 5 to

(A) n = 1

(B) n = 2

(C) n = 3

(D) n = 4

12. The first five ionization energies of an element are 801 , 2428 , 3660 , 25030 , 32835 in kJ/mol. Then the element could be

(A) a halogen

(B) a noble gas

(C) a third group element

(D) a second group element

13. The energy required to melt 1g ice is 33J. The number of quanta of radiation of frequency 4.67 ×1013 sec–1, that must be absorbed to melt 10 g ice is

(A) 1.065 × 1022

(B) 3.205 × 1023

(C) 9.076 × 1020

(D) none of these

14. If the wave length of first line of the Balmer series of hydrogen atom is 656.1 nm , the wave length of second line of this series would be

(A) 218.7 nm

(B) 328.0 nm

(C) 486.0 nm

(D) 640.0 nm

15. The energy of an electron in the first Bohr orbit for He+ ion is –54.4 eV. Which one of the following is a possible excited state for electron in Bohr orbit of He+ ion ?

(A) –6.04 eV

(B) – 6.8eV

(C) – 1.7 eV

(D) +1.36 eV

16. The outermost electronic configuration of the most electronegative element is

(A) ns2 , np3

(B) ns2 , np4

(C) ns2 , np5

(D) ns2 , np6

17. The first four ionization energies of an element are 191 , 578 , 872 and 5962 kcal. The number of valence electrons in the element is

(A) 1

(B) 2

(C) 3

(D) 4

18. The quantum numbers of +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.

19. A atom forms an ion by the loss of three electrons. The ion has an electronic configuration [Ar]3d6 . The symbol of the ion is

(A) Fe3+

(B) Ni3+

(C) Co3+

(D) Mn+3

20. Given that in H–atom , the transition energy for n = 1 to n = 2 is 10.2 eV , the energy for the same transition in Be3+ is

(A) 20.4 eV

(B) 30.6 eV

(C) 40.8 eV

(D) None of these