What is the mass of $33.6 \ dm^3$ of methane gas at $S.T.P.$?

In the petroleum industry,a process is carried out to increase the octane number of fuel as follows: $C_7H_{14} \rightarrow C_7H_8 + 3H_2$. In this process,two hydrocarbons are in liquid state while $H_2$ is in gaseous state. What is the percentage decrease in the weight of the liquid in the above reaction?

Based on the reaction $CH_4 + 2O_2 \to CO_2 + 2H_2O$,calculate the number of moles of oxygen required to react with $4.8 \, g$ of methane.

In what ratio by mass carbon dioxide $(CO_2)$ and nitrogen $(N_2)$ should be mixed so that the partial pressure exerted by each gas is the same?

$23 \ g$ of $Na$ will react with methyl alcohol to give:

$1 \text{ mole}$ of concentrated $HCl$ requires $X \text{ moles}$ of dilute $NaOH$ for neutralization,and $1 \text{ mole}$ of concentrated $H_2SO_4$ requires $Y \text{ moles}$ of dilute $NaOH$. Which of the following relations is true?