An aqueous solution contains 021 m hydrocyanic

Question

An aqueous solution contains 0.21 M hydrocyanic acid.

One Liter of this solution could be converted into a buffer by the addition of:

(Assume that the volume remains constant as each substance is added.)

•  0.10 mol HNO₃
•  0.21 mol NaCl
•  0.22 mol NaCN
•  0.052 mol Ba(OH)₂
•  0.22 mol HNO₃

An aqueous solution contains  0.26 M  ammonium iodide.  

One liter of this solution could be converted into a buffer by the addition of:

(Assume that the volume remains constant as each substance is added.)

•  0.12 mol HI
•  0.26 mol HI
•  0.25 mol NH₃
•  0.25 mol KI
•  0.06 mol Ba(OH)₂