NCERT Based Test: Electronic Configuration of Elements & The Periodic Table

Nuclear mass does not affect the valence shell because nucleus consists of protons and neutrons. Whereas proton, i.e. nuclear charge affects the valence shell but neutrons do not. Thus, option (c) is wrong.

Z = 12, 1s², 2s², 2p⁶, 3s² (n = 3)
Z = 17, 1s² 2s² 2p⁶ 3s² 3p⁵ (n = 3)

The element with atomic number 88 is radium (Ra).

Its electron configuration ends in 7s², indicating it belongs to:

• Group 2 of the periodic table.

(A) 3d-transition series, Z = 21 (Sc) to Z=30 (Zn)
(B) Lanthanoid series, Z = 58 (Ce) to Z = 71 (Lu)
(C) Actinoid series, Z = 90 (Th) to Z = 103 (Lr)
(D) 4d-transition Z = 39 (Y) to Z = 48 (Cd) series,

Z = 79 [Xe]4f¹⁴5d^10.6s¹ (n = 6)
As n = 6, the element belongs to 6^th period.
Group = ns + (n - I)d, I + 10 = 11