Classification Of Elements And Periodicity In Properties Ques 27
27. The first ionization potentials $(eV)$ of $Be$ and $B$ respectively are
[1998]
(a) $8.29,9.32$
(b) $9.32,9.32$
(c) $8.29,8.29$
(d) $9.32,8.29$
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Answer:
Correct Answer: 27.(d)
Solution:
(d) First ionisation potential of $Be$ is greater than boron due to following configuration $ _4 Be=1 s^{2}, 2 s^{2} \quad _5 B=1 s^{2}, 2 s^{2} 2 p^{1}$ Order of attraction of electrons towards nucleus $2 s>2 p$, so more amount of energy is required to remove the electron in $2 s$-orbital in comparison to $2 p$ orbital.
BETA
