(A) The Law of Conservation of Mass states that mass can neither be created nor destroyed during a chemical reaction.
This means that the total mass of the reactants must be equal to the total mass of the products.
Step $1$: Calculate the total mass of the reactants $(LHS)$:
$\text{Mass of reactants} = \text{Mass of sodium carbonate} + \text{Mass of acetic acid} = 5.3 \, g + 6 \, g = 11.3 \, g$.
Step $2$: Calculate the total mass of the products $(RHS)$:
$\text{Mass of products} = \text{Mass of sodium acetate} + \text{Mass of carbon dioxide} + \text{Mass of water} = 8.2 \, g + 2.2 \, g + 0.9 \, g = 11.3 \, g$.
Step $3$: Compare $LHS$ and $RHS$:
Since $LHS = RHS = 11.3 \, g$,the total mass remains conserved.
Therefore,these observations are in agreement with the law of conservation of mass.