What is the weight of carbon in $kg$ required to produce $270 \ kg$ of aluminum from bauxite by the Hall-Heroult process?

The amount of arsenic pentasulphide that can be obtained when $35.5 \ g$ of arsenic acid $(H_3AsO_4)$ is treated with excess $H_2S$ in the presence of conc. $HCl$ (assuming $100\%$ conversion) is $.... \ mol$.

What volume in liters is required to prepare a $0.1 \ N$ $HNO_3$ solution from $6.3 \ g$ of $HNO_3$?

What is the volume (in litres) of oxygen at $STP$ required for complete combustion of $32 \,g$ of $CH_4$? (Molecular weight of $CH_4$ is $16$)

Zinc reacts with hydrochloric acid to give hydrogen and zinc chloride. The volume of hydrogen gas produced at $STP$ from the reaction of $11.5 \ g$ of zinc with excess $HCl$ is $.......... \ L$ (Nearest integer) (Given: Molar mass of $Zn$ is $65.4 \ g \ mol^{-1}$ and Molar volume of $H_2$ at $STP = 22.7 \ L$)

Equal masses of ethane $(C_2H_6)$ and hydrogen $(H_2)$ are mixed in an empty container at $298 \ K$. The fraction of total pressure exerted by hydrogen is: