According to the Law of Conservation of Mass, the mass of the reactants must equal the mass of the products. In this case, we know that 98 g of carbon dioxide (CO2) is produced and 24 g of carbon (C) is used in the reaction.
To find the mass of dioxygen (O2) in the reactants, we can use the following equation:
Mass of reactants = Mass of products
Let \( x \) be the mass of dioxygen (O2). Then we can write:
\[ x + 24 , \text{g (mass of carbon)} = 98 , \text{g (mass of carbon dioxide)} \]
Now, solving for \( x \):
\[ x = 98 , \text{g} - 24 , \text{g} \] \[ x = 74 , \text{g} \]
So, the mass of dioxygen (O2) in the reactants is 74 g.