Which of the following is most acidic?

Observe the following oxides. The number of amphoteric oxides from the given list is
$CO, B_2O_3, SnO_2, PbO_2, Ga_2O_3, SnO, PbO, CO_2$

Regarding $F^{-}$ and $Cl^{-}$,which of the following statements is/are correct?
$(i)$ $Cl^{-}$ can give up an electron more easily than $F^{-}$
$(ii)$ $Cl^{-}$ is a better reducing agent than $F^{-}$
$(iii)$ $Cl^{-}$ is smaller in size than $F^{-}$
$(iv)$ $F^{-}$ can be oxidized more readily than $Cl^{-}$

The periodic table consists of $18$ groups. An isotope of copper,on bombardment with protons,undergoes a nuclear reaction yielding element $X$ as shown below. To which group,element $X$ belongs in the periodic table?
${}_{29}^{83}Cu + {}_{1}^{1}H \rightarrow 6{}_{0}^{1}n + {}_{2}^{4}\alpha + 2{}_{1}^{1}H + X$

Red hot carbon will remove oxygen from the oxides $XO$ and $YO$ but not from $ZO$. $Y$ will remove oxygen from $XO$. Use this evidence to deduce the order of activity of the three metals $X, Y$ and $Z$ putting the most active first.

Aluminium is diagonally related to (in periodic table)