Inert pair effect is shown by how many elements?

$Ga,Al,Tl,Pb,Sn,Ge$

Q. Out of the elements $C,S,Ge,Sn$ and $Pb$, only $+4$ oxidation state is shown by how many element(s)?

Q. Which of the following option correctly represent the correct set of stability order for the given ions?
(I) $G{a}^{3+}>I{n}^{3+}>T{l}^{3+}$
(II) $G{a}^{3+}<I{n}^{3+}<T{l}^{3+}$
(III) $G{e}^{+4}>S{n}^{+4}>P{b}^{+4}$
(IV) $G{e}^{+2}<S{n}^{2+}<P{b}^{2+}$
(V) $A{s}^{3+}<S{b}^{3+}<B{i}^{3+}$

Q. How many of following elements will liberate $H_2$ gas when treated with dil $HN{O}_3$?
Mg, Zn, Sn, Pb

Q. Among the following, the elements which produce $H_2$ gas upon reaction with $NaOH.$
$Mg,Ca,Al,Zn,Pb,Sn,SiC,C$

Q. The oxidation state(s) shared by each of the elements in group IV $(C,Si,Ge,Sn$ and $Pb)$ is/are