Which pair of substances gives the same gaseous product when they react with water?

On heating $ZnCl_2 \cdot 2H_2O$,the compound obtained is

Which of the following alloys contains a non-metal?

Select the correct statement :-
$(a)$ $CaSO_4 \cdot 2H_2O \xrightarrow{393 \ K} CaSO_4 \cdot \frac{1}{2}H_2O + \frac{3}{2}H_2O$
$(b)$ $3Br_2 + 6NaOH \xrightarrow{\text{hot & conc.}} 5NaBr + NaBrO_3 + 3H_2O$
$(c)$ $3Mg + N_2$ $\rightarrow Mg_3N_2$ $\xrightarrow{6H_2O} 3Mg(OH)_2 + 2NH_3 \uparrow$
$(d)$ $2Be + C$ $\rightarrow Be_2C$ $\xrightarrow{4H_2O} 2Be(OH)_2 + CH_4 \uparrow$
Correct answer is :-

Identify the correct statements from the following:
$I$. $LiF$ is less soluble in water than $NaF$
$II$. Both $LiCl$ and $MgCl_2$ are insoluble in ethanol
$III$. Both $Li$ and $Mg$ form nitrides
$IV$. $Na_2CO_3$ gives $CO_2$ on heating

The alloy used in the construction of aircraft is