The screening effect of inner electrons of the nucleus causes

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?

Which of the following statements is correct about the "shielding effect"?
$1$. It is effective when the orbitals in the inner shells are completely filled.
$2$. Inner shells do not show any effect.
$3$. With an increase of shielding down the group,ionization energy increases.
$4$. With increasing nuclear charge,the shielding effect increases.

The core charge on oxygen is equal to $-$

In a given shell,the order of screening effect is

In which pair does the first element have a higher $Z_{eff}$ than the second atom?