Gases emitted during volcanic activity often contain high concentrations of hydrogen sulfide and sulfur dioxide. these gases may react to produce deposits of sulfur according to the equation: 2 h2s(g) so2(g) → 3 s(s) 2 h2o(g) for the complete reaction of 6.41 mol of hydrogen sulfide:

There can be three possible answers to this question: the amount of moles of SO₂ gas needed to react with 6.41 mol H₂S, and the amount of S and H₂O gas produced.

Amount of SO₂:
6.41 mol H₂S (1 mol SO₂/2 mol 2 mol H₂S) = 3.205 moles SO₂ gas

Amount of S:
6.41 mol H₂S (3 mol S/2 mol 2 mol H₂S) = 9.615 moles S solid

Amount of H₂O:
6.41 mol H₂S (2 mol H₂O/2 mol 2 mol H₂S) = 6.41 moles H₂O gas

The answer is c - the principal of original lateral continuity.