Yes. Avogadro Law gives the relationship between volume and amount when pressure and temperature are held constant. Remember amount is measured in moles. This means the gas pressure inside the container will increase (for an instant), becoming greater than the pressure on the outside of the walls.
60 Grams are produced due to the fact that it may not produce more due to the certain capacity that varies on the size of the cube.
Answer:
I think it would be:
NaCO3 (s)-->Na2O (s) + CO2 (g)
