Question

The first ionisation potential (in eV) of Be and B, respectively are

• A. 8.29, 9.32
• B. 9.32, 9.32
• C. 8.29, 8.29
• D. 9.32, 8.29

Answer 1

Answer: (D)

9.32, 8.29

Answer 2

First ionisation potential of Be is greater than
boron due to stable configuration
$\, \, \, \, \, \, \, \, \, \, _4 Be =1s^2 , 2s^2$
$\, \, \, \, \, \, \, \, \, \, _5 B=1s^2,2s^2 2p^1$
Order of attraction of electrons towards nucleus is 2s >2p, so more amount of energy is required to remove the electron from 2 s orbital in comparison to 2p orbital. So, ionisation potential of Be is 9.32 eV and B is 8.29 eV