36.8mL of hydrogren gas, from the reaction of a piece of magnesium ribbon with hydrochloric acid, are collected over water in a eudiometer. The temp of the hydrogen gas at 21C, and the atmospheric pressire is 768mmHg. The vapor pressire of water at 21C is 18.7mmHg (torr). What is the original mass of magnesium? (R=0.08206L*atm/mol*K)
A) 1.07 g
B) 0.0211 g
C) 1.143 g
D) 0.0366 g
E) 0.0392 g