Which of the following combinations can result in the formation of a buffer?

Which one of the following combinations does not create a buffer?

 Which of the following combinations can result in the formation of a buffer?

A buffer solution is comprised of 50.0 mL of a 0.100 M HC₂H₃O₂ and 60.0 mL of a 0.100 M NaC₂H₃O₂. Which of the following actions would completely destroy the buffer?

Calculate the pH of a solution formed by mixing 200 mL of a 0.400 M C₂H₅NH₂ solution with 350 mL of a 0.450 M C₂H₅NH₃⁺ solution. (K_b of C₂H₅NH₂ is 5.6 x 10 ^-4).

Determine how many grams of sodium acetate, NaCH₃CO₂ (MW:82.05 g/mol), you would mix into enough 0.065 M acetic acid CH₃CO₂H (MW:60.05 g/mol) to prepare 3.2 L of a buffer with a pH of 4.58. The K_a is 1.8 x 10^-5.