How many liters of $CO_2$ gas are released at $STP$ upon the complete decomposition of $9.85 \ g$ of $BaCO_3$ (Atomic mass of $Ba = 137$)?

$0.7 \ g$ of $Na_2CO_3 \cdot xH_2O$ were dissolved in water and the volume was made to $100 \ mL$. $20 \ mL$ of this solution required $19.8 \ mL$ of $N/10 \ HCl$ for complete neutralization. The value of $x$ is:

The amount of metallic $Zn$ (atomic weight $= 65.4$) required to react with aqueous sodium hydroxide to produce $1 \ g$ of $H_2$ is $.... \ g$.

The number of moles of methane required to produce $11 \ g$ of $CO_{2(g)}$ after complete combustion is:
(Given molar mass of methane in $g \ mol^{-1}: 16$)

The mass of $BaCO_3$ produced when excess $CO_2$ is bubbled through a solution of $0.205 \ mol$ $Ba(OH)_2$ is ............ $g$.

$A$ person consumes $640 \, g$ of $O_2$ daily. If all the $O_2$ is used for the conversion of sugar into $CO_2$ and $H_2O$,how much sucrose $(C_{12}H_{22}O_{11})$ is consumed in the body per day and how much heat in $kJ$ is produced (in $.33$)? Given: $\Delta H_{combustion} \text{ of sucrose} = -5645 \, kJ \, mol^{-1}$.