Question

Please explain to me thank you.

Which one of the following aqueous solutions, when mixed with an equal volume of 0.10 mol L^-1 aqueous NH₃, will produce a buffer solution?

A) 0.10 mol L^-1 CH₃COOH

B) 0.050 mol L^-1 NaOH

C) 0.20 mol L^-1 NH₄Cl

D) 0.20 mol L^-1 HCl

E) 0.10 mol L^-1 HCl

NUMBER 2

Which of the following has the highest buffer capacity?

A) 0.10 M H₂PO₄^- / 0.10 M HPO₄^2-

B) 0.50 M H₂PO₄^- / 0.10 M HPO₄^2-

C) They all have the same buffer capacity.

D) 0.10 M H₂PO₄^- / 0.50 M HPO₄^2-

E) 0.50 M H₂PO₄^- / 0.50 M HPO₄^2-

^{NUMBER 3}

Which of the following acids should be used to prepare a buffer with a pH of 4.5?

A) HBrO, K_a = 2.3 ✕ 10^-9

B) CH₃COOH, K_a = 1.8 ✕ 10^-5

C) C₅H₅O₅COOH^-2, K_a = 4.0 ✕ 10^-6

D) C₆H₄(COOH)₂, K_a = 2.9 ✕ 10^-4

E) HOC₆H₄OCOOH, K_a = 1.0 ✕ 10^-3