The value of $x$ in $KAl(SO_4)_x \cdot 12 H_2O$ is $.....$

The mass percentage of nitrogen in histamine is

An organic compound has an empirical formula $CH_2O$,its vapour density is $45$. The molecular formula of the compound is

Calculate the percentage composition of element $P$ in ${H_3PO_4}$. (in $\%$)

The elemental composition of a compound is $54.2 \% C$,$9.2 \% H$,and $36.6 \% O$. If the molar mass of the compound is $132 \ g \ mol^{-1}$,the molecular formula of the compound is: [Given: The relative atomic mass of $C:H:O = 12:1:16$]

Calculate the mass percent of calcium,phosphorus,and oxygen in calcium phosphate $Ca_{3}(PO_{4})_{2}$.