Which gas is evolved when $SiO_2$ reacts with sodium carbonate?

$(a)$ Classify the following oxides as neutral,acidic,basic,or amphoteric:
$CO, B_2O_3, SiO_2, CO_2, Al_2O_3, PbO_2, Tl_2O_3$
$(b)$ Write suitable chemical equations to show their nature.

What are silicones?

Which one of the following is used to convert sunlight into electricity in photovoltaic material?

$SnCl_2$ acts as a reducing agent because:

The group $14$ elements $A$ and $B$ have the first ionisation enthalpy values of $708$ and $715 \ kJ \ mol^{-1}$ respectively. These values are the lowest among their group members. The nature of their ions $A^{2+}$ and $B^{4+}$ respectively is: