$30.$ Indicate whether the mass would "increase", "decrease", or "stay the same" for the following scenarios where chemical reactions take place:

Chemical equation: $2$Mg$($s$)+$ O$($g$)->2$MgO$($s$)$

$($a$)$When magnesium burns in air a white flaky ash of magnesium oxide is produced. Is the mass of magnesium oxide less than, greater than, or the same as the original piece of magnesium? Explain.

$($b$)$ Antoine Lavoisier, the French scientist credited with first stating the law of conservation of matter, heated a mixture of tin and air in a sealed flask to produce tin oxide. Did the mass of the sealed flask and contents decrease, increase, or remain the same after the heating? Explain

$31.$ Yeast converts glucose to ethanol and carbon dioxide during anaerobic fermentation as depicted in the simple chemical equation here:

glucose $$ ethanol $+$ carbon dioxide

$($a$)$ If $199\mathrm{.}4$ g of glucose is fully converted, what will be the total mass of ethanol and carbon dioxide produced? Explain

$($b$)$ If the fermentation is carried out in an open container, would you expect the mass of the container and contents after fermentation to "decrease", "increase", or "stay the same"? Explain

$($c$)$ If $96\mathrm{.}7$ g of carbon dioxide is produced, what mass of ethanol is produced in part a$?$ Show your work.