Find the volume of $56 \ g$ of dinitrogen $(N_2)$ at $STP$. (in $L$)

$0.7 \ g$ 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:

$150 \ g$ $CaCO_3$ sample was taken. On its complete decomposition $56 \ g$ $CaO$ is produced. The $\%$ purity of the sample is .............. $\%$

The weight of oxalic acid required to neutralize $100 \, cc$ of a normal solution of $NaOH$ is ........ $gm$.

Dehydration of cyclohexanol $(C_6H_{11}OH)$ to cyclohexene $(C_6H_{10})$ gives a yield of $75\%$. If $100 \ g$ of cyclohexanol is dehydrated,what is the mass of the product obtained in grams?

What will be the volume of $O_2$ gas at $STP$ for complete combustion of $7.8 \ g$ acetylene? ............ $L$