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 $atm$?

When $1 \ L$ of $CO_2$ gas is heated with graphite,the volume of the resulting gas mixture at $STP$ is $1.5 \ L$. Calculate the number of moles of $CO$ gas produced at $STP$.

$20 \, mL$ of a $1 \, N$ solution of $KMnO_4$ just reacts with $20 \, mL$ of a solution of oxalic acid. The weight of oxalic acid crystals in $1 \, L$ of the solution is $... \, g$

Change in volume when $10 \, mL$ of phosphine $(PH_3)$ is decomposed according to the reaction: $2PH_{3(g)} \rightarrow 2P_{(s)} + 3H_{2(g)}$.

Magnetite can be reduced with $CO$ to yield iron metal and carbon dioxide. Calculate the mass of magnetite (in $kg$) needed to obtain $4 \ kg$ of iron if the process is $80 \%$ efficient. [Atomic weight of $Fe$ and $O$ are $56 \ g$ and $16 \ g$, respectively]

$A$ solid mixture weighing $5 \ g$ contains equal number of moles of $Na_2CO_3$ and $NaHCO_3$. This solid mixture was dissolved in $1 \ L$ of water. What is the volume (in $mL$) of $0.1 \ M \ HCl$ required to completely react with this $1 \ L$ mixture solution?