The nitrate of which metal does not give nitrogen dioxide on strong heating?

Nitrates of all metals are:

What is the product formed when $Zn$ reacts with an excess of $NaOH$?

$2Na_2O \overset{400 \ ^oC}{\rightleftharpoons} A + 2Na$
$A + SO_2 \to Na_2SO_4$
$A + CO \to Na_2CO_3$
In the above reaction,$A$ is:

Which of the following alloys are correctly matched with their uses?
$(i)$ $Li-Mg$ armour plates
$(ii)$ $Cu-Be$ high strength springs
$(iii)$ $Mg-Al$ aircraft construction

Which of the following ions forms a highly soluble hydroxide in water?