$0.5$ mole of ${\mathrm{H}}_2{\mathrm{SO}}_4$ is mixed with $0.2$ mole of $\mathrm{Ca}\left({\mathrm{OH}}_2\right)$. The maximum number of moles of ${\mathrm{CaSO}}_4$ formed is

What weight of ${\mathrm{CaCO}}_3$ must be decomposed to produce the sufficient quantity of carbon dioxide to convert $21.2\mathrm{kg}$ of  ${\mathrm{Na}}_2{\mathrm{CO}}_3$ completely in to ${\mathrm{NaHCO}}_3$ [Atomic mass $\mathrm{Na}=23,\mathrm{Ca}=40$]
${\mathrm{CaCO}}_3⟶\mathrm{CaO}+{\mathrm{CO}}_2$

${\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}\to 2{\mathrm{NaHCO}}_3$

$\mathrm{NX}$ is produced by the following step of reactions:

$\mathrm{M}+{\mathrm{X}}_2⟶{\mathrm{MX}}_2$
$3{\mathrm{MX}}_2+{\mathrm{X}}_2⟶{\mathrm{M}}_3{\mathrm{X}}_8$
${\mathrm{M}}_3{\mathrm{X}}_8+{\mathrm{N}}_2{\mathrm{CO}}_3⟶\mathrm{NX}+{\mathrm{CO}}_2+{\mathrm{M}}_3{\mathrm{O}}_4$

How much $\mathrm{M}$ (metal) is consumed to produce $206 \mathrm{g}$ of $\mathrm{NX}$. (Take at $\mathrm{wt}$of $\mathrm{M}=56, \mathrm{N}=23, \mathrm{X}=80$)

The following process has been used to obtain iodine from oil-field brines in California.

$\mathrm{Nal}+{\mathrm{AgNO}}_3⟶\mathrm{Agl}+{\mathrm{NaNO}}_3$; 

$2\mathrm{Agl}+\mathrm{Fe}\to {\mathrm{Fel}}_2+2\mathrm{Ag}$

$2{\mathrm{Fel}}_2+3{\mathrm{Cl}}_2⟶2{\mathrm{FeCl}}_3+2{\mathrm{l}}_2$

How many grams of ${\mathrm{AgNO}}_3$ are required in the first step for every $254 \mathrm{kg} {\mathrm{I}}_2$ produced in the third step.