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?

What is the weight of the precipitate formed when $50 \ mL$ of $16.9 \%$ $AgNO_3$ solution is mixed with $50 \ mL$ of $5.8 \%$ $NaCl$ solution (in $g$)?

Equal masses of methane $(CH_4)$ and oxygen $(O_2)$ are mixed in an empty container at $25\,^oC$. The fraction of the total pressure exerted by oxygen is:

The weight of oxalic acid required to neutralize $100 \, cc$ of a normal solution of $NaOH$ is ........ $gm$.

Sodium oxide reacts with water to produce sodium hydroxide. $20.0 \ g$ of sodium oxide is dissolved in $500 \ mL$ of water. Neglecting the change in volume,the concentration of the resulting $NaOH$ solution is $........ \times 10^{-1} \ M.$ (Nearest integer)
[Atomic mass $: Na=23.0, O=16.0, H=1.0]$

When $CO_2$ is bubbled through $0.205 \ mol$ of $Ba(OH)_2$,how many grams of $BaCO_3$ will be produced?