(1)2NaHCO3 == NaCO3 + CO2 + H2O
-------2mol---------------------44g----18g----62g
------0.025mol--------------------------------------------1.55g
(2)n(NaHCO3) == 0.025mol
n(Na2CO3) == (10 - 84*0.025)/106 == 0.075mol
(3)V(CO2) == 22.4*(0.025 + 0.075)
== 2.24L !
OK!