Find the volume of $56 \ g$ of dinitrogen $(N_2)$ at $STP$. (in $L$)

$A$ $100 \ mL$ solution was made by adding $1.43 \ g$ of $Na_2CO_3 \cdot xH_2O$. The normality of the solution is $0.1 \ N$. The value of $x$ is .......... (The atomic mass of $Na$ is $23 \ g/mol$):

The volume of $0.1 \, M$ aqueous $KOH$ solution required for the complete neutralization of $20 \, mL$ of $0.1 \, M$ aqueous $H_3PO_3$ solution is .......... $mL$.

As per the following equation, $0.217 \ g$ of $HgO$ (molecular mass $= 217 \ g \ mol^{-1}$) reacts with excess iodide. On titration of the resulting solution, how many $mL$ of $0.01 \ M$ $HCl$ is required to reach the equivalence point (in $mL$)?
$HgO + 4 I^{-} + H_2O \longrightarrow HgI_4^{2-} + 2 OH^{-}$

$19 \ g$ of a mixture containing $NaHCO_3$ and $Na_2CO_3$ on complete heating liberated $1.12 \ L$ of $CO_2$ at $STP$. The weight of the remaining solid was $15.9 \ g$. What is the weight (in $g$) of $Na_2CO_3$ in the mixture before heating?

How much $g$ of $NaOH$ is required to neutralize $1500 \, cm^3$ of $0.1 \, N$ $HCl$ (At. wt. of $Na = 23$)?