Which of the four solutions is the best buffer against addition of acid or base? a. na2hpo4 b. na2hpo4 + nah2po4 c. nah2po4 d. h2o submit for grading save and finish later?

b. Na2HPO4 + NaH2PO4.

A buffer is a solution of a weak acid and its conjugate base. The weak acid is H2PO4^(-) and its conjugate base is HPO4^(2-).

All the other options are incorrect because they consist of only a single component.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6