Which of the Following Mixtures Will Be a Buffer When

Multiple Choice

Which of the following mixtures will be a buffer when dissolved in a liter of water?

A) 0.4 mol NH₃ and 0.4 mol HCl
B) 0.3 mol NaCl and 0.3 mol HCl
C) 0.1 mol Ca(OH) ₂ and 0.3 mol HI
D) 0.2 mol H₃PO₄ and 0.1 mol NaOH
E) 0.2 mol HBr and 0.1 mol NaOH