21. The relative (average) atomic mass of oxygen is 16.00. Given this, which of the following is true regarding the relative natural abundance of the isotope 18/8 O

Bridget is in science class. her teacher gives her two unknown substances and asks her to determine their relative ph. she places a piece of red litmus paper into both substances. the litmus paper turns purple when she places it into substance i. the litmus paper turns blue when she places it into substance ii. a. substance i is a neutral substance and substance ii is an acid. b. substance i is a neutral substance and substance ii is a base. c. substance i is an acid and substance ii is a base. d. substance i is a base and substance ii is a neutral substance.