The core charge on oxygen is equal to $-$

The order of screening effect among $s, p, d$ and $f$-orbitals of a given shell of an atom on its outer shell electrons 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?

How does the orbital energy change as the nuclear charge increases from $Ne$ to $Ca$?

If $Z_{eff}$ of $B$ is $2.6$,then the value of $Z_{eff}$ of oxygen and fluorine will be :-

The unpaired electrons in $Al$ and $Si$ are present in the $3p$ orbital. Which electrons will experience more effective nuclear charge from the nucleus?