ATOMS AND MOLECULES question bank (Science)

In a reaction,$5.3 \, g$ of sodium carbonate reacted with $6 \, g$ of acetic acid. The products were $2.2 \, g$ of carbon dioxide,$0.9 \, g$ of water,and $8.2 \, g$ of sodium acetate. Show that these observations are in agreement with the law of conservation of mass.
$\text{Sodium carbonate} + \text{Acetic acid} \to \text{Sodium acetate} + \text{Carbon dioxide} + \text{Water}$

Hydrogen and oxygen combine in the ratio of $1:8$ by mass to form water. What mass of oxygen gas would be required to react completely with $3 \,g$ of hydrogen gas (in $,g$)?