If the concentration of compound $AB_5$ is $10^{-3} \text{ mol/L}$,then the concentration of $B^{-}$ will be .......

$A$ gaseous mixture contains $50\%$ Helium and $50\%$ Methane by volume. What is the percentage of Methane by weight in the mixture?

Two elements $A$ and $B$ form $0.15 \ mol$ of $A_2 B$ and $AB_3$ type compounds. If $0.15 \ mol$ of both $A_2 B$ and $AB_3$ weigh equally,then the atomic weight of $A$ is $...$ times the atomic weight of $B$.

In $Fe_{0.96}O$,$Fe$ is present in $+2$ and $+3$ oxidation states. What is the mole fraction of $Fe^{2+}$ ions in the compound?

How much oxygen is required for complete combustion of $560 \ g$ of ethene? ................. $kg$

$25 \, mL$ of a decinormal $NaOH$ solution is completely neutralized by $0.16 \, g$ of a dibasic acid. The molecular weight of the dibasic acid is: