Which of the following solutions result in a buffer ?

Question

a) 0.100 L of 0.250 M CH3COOH + 0.050 L of 0.250 M NaOH


b) 0.100 L of 0.250 M CH3COOH + 0.050 L of 0.250 M HCl


c) 0.050 L of 0.250 M CH3COONa + 0.100 L of 0.250 M HCl


d) 0.100 L of 0.250 M CH3COONa + 0.050 L of 0.250 M HCl



It's not b, bd, or d.

Any help with an explaination is appreciated. Thank you.

Answer 1

In a, half of the acid is neutralised, leaving half of the acid unchanged = a buffer.

In d, half of the salt is changed back into the acid, leaving half the salt = a buffer.