Explanation:
Atomic number of hydrogen is 1 as it is the very first element of periodic table.
Hence, electronic configuration of hydrogen is [tex]1s^{1}[/tex].
On the other hand, second element of the periodic table is helium and its atomic number is 2. Helium is also known as a noble gas.
Therefore, electronic configuration of helium is [tex]1s^{2}[/tex].
Thus, we can conclude that electronic configuration of hydrogen and helium is [tex]1s^{1}[/tex] and [tex]1s^{2}[/tex].
