Which of these reactions will produce a buffer

All components are present in 0.10 M concen- trations.
I) HCN and NaCN
II) NH3 and NH4Cl
III) HNO3 and NH4NO3
IV) HClO3 and NaClO3
Which will give buffer solutions?
1. II, III and IV only
2. I and III only
3. I, III and IV only
4. III and IV only
5. I and II only

5 I and II only

I) acidic buffer is formed with weak acid and a salt of weak acid with strong base
II)basic buffer is formed with weak base and a salt of weak base with strong acid

HNO3 and HClO3 are strong acids so they cant form buffer

see this link--
http://www.thebigger.com/chemistry/ionic…