In $Lithium$,the $2s$ electron experiences a force of attraction exerted by the nucleus that is:

The bromine atom possesses $35$ electrons. It contains $6$ electrons in $2p$ orbital,$6$ electrons in $3p$ orbital and $5$ electrons in $4p$ orbital. Which of these electrons experiences the lowest effective nuclear charge?

For the valence shell of $Na$,screening is provided by:

Arrange $s, p, d,$ and $f$ subshells of a shell in the increasing order of effective nuclear charge $(Z_{eff})$ experienced by the electron present in them.

Among the following,the energy of $2s$ orbital is lowest in

The screening effect of inner electrons of the nucleus causes