The reactions are as follows:
(a) 2H2O(l)⟶2H2(g)+O2(g)]×0.75
(b) N2(g)+3H2(g)⟶2NH3(g)]×0.50
(c) CaCO3(s)⟶CaO(s)+CO2(g)]
(d) NH3(g)+CO2(g)+H2O(l)⟶NH4HCO3(aq)
0.75× (a) +0.50× (b) gives,
0.5N2(g)+15H2O(l)⟶NH3(g)+0.75O2(g)
Thus, N2(g)required=0.05molfor0.1molNH4HCO3.
H2O(l)required=0.15molin(a)and(b)+0.10molinfinalreaction=0.25mol.
So, the value of y is 25.