Which of the following solution(s) would be a buffer? Select all that apply. a. 100.0 mL of a solution that contains 0.100 M benzoic acid and 0.100 M potassium benzoate
b. 100.0 mL of a 0.100 M propanoic acid to which 50.0 mL of 0.100 M sodium hydroxide has been added
c. 100.0 mL of a 0.100 M formic acid solution
d. 100.0 mL of a solution that contains 0.100 M hydrochloric acid and 0.100 M sodium chloride
e. 100.0 mL of a 0.100 M solution of acetic acid in which 0.100 g of sodium acetate is dissolved