Question

In which of the following electronic configuration an atom has the lowest ionisation enthalpy?
(a) 1s² 2s² 2p³
(b) 1s² 2s² 2p⁵ 3s¹
(c) 1s² 2s² 2p⁶
(d) 1s² 2s² 2p⁵

Answer 1

b) is the answer.

because if the distance between the nucleus and electrons increases then the ease of removing electrons becomes easier.

hope this helps u.

Answer 2

Answer: b. $1s^22s^2p^63s^1$

Explanation:

The ionization energy is the energy required to remove an electron from the valence shell of an isolated gaseous atom of an element.

Now the ionization energy depends upon

a) size of an element ,larger the size more lesser the effective nuclear charge on electron thus lower the ionization energy.

b) the electronic configuration of an element. If on losing an electron an element attains noble gas configuration or half filled stability then it will easily lose an electron.

Thus the configuration $1s^22s^2p^63s^1$ will easily lose its electron to attain stable configuration of $1s^22s^2p^6$ and thus has lowest ionization enthalpy.