The primary matallic element that's added to stool to make stainless steel is

Carbon, a nonmetallic element, forms a number of organic and inorganic compounds and can be found in coal, petroleum and limestone. It is the principle strengthening element in carbon steels and low-alloy steels. Atomic number 6, atomic weight 12.01115.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

the answer is b, have negligible mass