$A$ $100 \ mL$ 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 $23 \ g/mol$):

Amount of oxygen required for combustion of $1 \, kg$ of a mixture of butane and isobutane is ............. $kg$.

If $V \ mL$ of a substance at $NTP$ weighs $W \ g$,then the molecular weight of the substance is....

$100 \ mL$ of $0.1 \ N$ hypo solution is decolourised by the iodine liberated from the addition of $x \ g$ of crystalline copper sulphate to an excess of $KI$. The value of $x$ is ............. $g$ (molecular weight of $CuSO_4 \cdot 5H_2O$ is $250$).

Calculate the amount of water $(g)$ produced by the combustion of $16 \ g$ of methane. (in $g$)

How many moles of ferric alum $(NH_4)_2SO_4 \cdot Fe_2(SO_4)_3 \cdot 24H_2O$ can be made from a sample of $Fe$ containing $0.0056 \ g$ of it?