Argon has 24 known isotopes.
mass (m) = ? , volume = 18.0 ml , density = 1.42 g/ml .

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Answer:
The coefficient is 1
Explanation:
CaO(s) + CO2(g) -> CaCO3(s)
In the balanced equation, the coefficient for CaO is 1
The coefficient represents the number of moles of a compound in the stoichiometry of the reaction