$A$ $100 \ mL$ solution was made by adding $1.43 \ g$ of $Na_2CO_3 \cdot xH_2O$. The normality of the solution is $0.1 \ N$. The value of $x$ is .......... (The atomic mass of $Na$ is $23 \ g/mol$):

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

If $50 \ mL$ of $0.5 \ M$ oxalic acid is required to neutralize $25 \ mL$ of $NaOH$ solution, the amount of $NaOH$ in $50 \ mL$ of the given $NaOH$ solution is . . . . . . $g$.

If the percentage purity of an impure sample of a compound is given,then the weight of the substance required to prepare its $0.1 \, N$ solution will be:

If a sample of $8.3 \ mL$ of $H_2SO_4$ $(36 \ N)$ is diluted with $991.7 \ mL$ of water,what is the approximate concentration of the resulting solution (in $N$)?

When a certain amount of ethylene is combusted,$6226 \, kJ$ of heat is released. If its enthalpy of combustion is $1411 \, kJ \, mol^{-1}$,the number of oxygen atoms consumed in the process at $STP$ will be ............... $N_A$.