# Among the following,

Question:

Among the following, the energy of $2 \mathrm{~s}$ orbital is lowest in :

1. $\mathrm{K}$

2. $\mathrm{Na}$

3. $\mathrm{Li}$

4. $\mathrm{H}$

Correct Option: 1

Solution:

In 'K', 2s orbital feel maximum attraction from nucleus (So having less energy) due to more $\mathrm{Z}_{\text {eff }}$.