Question

Na2O-NaOH-Na2CO3-CO2-CaCO3-CO2

Answer 1

$\boxed{\bf Na_2O \to NaOH \to Na_2CO_3 \to CO_2 \to CaCO_3 \to CO_2}$
$\tt 1)~Na_2O + H_2O \to 2NaOH.$

$\tt 2)~2NaOH + (NH_4)_2CO_3 \to 2NH_3\uparrow + 2H_2O + Na_2CO_3$

$\tt 3)~Na_2CO_3 + 2HCl \to CO_2\uparrow + H_2O + 2NaCl.$

$\tt 4)~Ca(OH)_2 + CO_2 \to CaCO_3\downarrow + H_2O.$
$\tt 5)~CaCO_3 \xrightarrow{t^{\circ}C} CaO + CO_2\uparrow.$