What is the quantity of hydrogen gas liberated when $46 \ g$ sodium reacts with excess ethanol? (Given Atomic mass of $Na = 23$)

The amount of $50\% \ (w/w)$ solution of hydrochloric acid required to react with $200 \ g$ of $CaCO_3$ would be (in $g$)

White phosphorus reacts with chlorine and the product hydrolyses in the presence of water. Calculate the mass of $HCl$ obtained by the hydrolysis of the product formed by the reaction of $62 \ g$ of white phosphorus with chlorine in the presence of water.

Equal masses of $SO_2$,$CH_4$,and $O_2$ are placed in an empty container at $298 \ K$. The total pressure is $2.1 \ atm$. What is the partial pressure of $CH_4$ in the mixture in $atm$?

$29.2 \% (w/w)$ $HCl$ stock solution has a density of $1.25 \ g \ mL^{-1}$. The molecular weight of $HCl$ is $36.5 \ g \ mol^{-1}$. The volume $(mL)$ of stock solution required to prepare a $200 \ mL$ solution of $0.4 \ M$ $HCl$ is :

The heat of combustion of methane is $-800 \ kJ \ mol^{-1}$. What is the heat of combustion for $4 \times 10^{-4} \ kg$ of methane?