Question

Which one among the following has a filled $4p$ orbital?

• A. Na
• B. Fe
• C. $C{l}^{-}$
• D. $Rb$
• E. $C{a}^{+}$

Answer 1

Answer: (D)

$Rb$

Rb has a filled 4p orbital. The atomic number of Rb is 37. Its electronic configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^1$.
The electronic configurations of other species are as given below.
$Na:1s^{2}2s^{2}2p^{6}3s^1$
$Fe:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$
$C{l}^{-}:1s^{2}2s^{2}2p^{6}3s^{2}3p^6$
$C{a}^{+}:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$