Answer:
One mole of SnO2
Explanation:
SnO2(s) + 2H2(g) ------> Sn(s) + 2H2O(l)
In every question that has to do with stoichiometry, the balanced reaction equation is the first step towards obtaining the correct answer because it serves as a guide in solving the question.
From the balanced reaction equation, we have
1 mole of SnO2 reacts with 2 moles of hydrogen gas to yield two moles of water.
The balanced reaction equation represents one mole of SnO2.
Hence the answer.