Answer:
SnO2
Explanation:
The limiting reactant is the reactant that runs out first during a chemical reaction.
Reactants are on the left side of the reaction, so SnO2 and H2. They tell us in the question that there is "excess" hydrogen (H2), so we know there is plenty of it, as "excess" means "more than enough." If we have more than enough hydrogen, then we know that we will run out of SnO2 first.
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