At the beginning of this lesson, there was a question about two acids. vinegar, which contains acetic acid, is used in foods and has few safety concerns. hydrochloric acid is used in chemistry labs and requires the use of safety goggles and gloves. why do the safety concerns for these two acids differ?

Acetic acid is a weak acid and an organic compound and as such is not corrosive and therefore is acceptable to be used in food in the form of vinegar whereas hydrochloric acid is a strong mineral acid (partially derived from rock salt) and it is corrosive and from the author's experience it can be used in dilute form ie 10% by volume to react with limestone as a diagnostic test for that rock type (the limestone fizzes upon reaction with the dilute HCL.

And a) oxygen i believe