a student heats a compound to constant mass and then leaves it sit out for a few hours. She comes back, remanded the sample and finds it has a greater mass than before. Explain how this could happen. ANY HELP IS MUCH APPRECIATED! :)

am i too late?

explanation:

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.