The correct option is C 100 mL of 0.1 M HCl+200 mL of 0.1M NH4OH
CH3COOH1) 25 mL×0.1 M=2.5 mmol0+NaOH50 mL×0.1 M=5 mmol2.5 mmol→CH3COONa02.5 mmol+H2O
This is basic solution due to NaOH. This is not basic buffer.
CH3COOH2) 100 mL×0.1 M=10 mmol0+NaOH100 mL×0.1M=10 mmol0→CH3COONa010 mmol+H2O
Hydrolysis of salt takes place. This is not buffer.
HCl3) 100 mL×0.1 M=10 mmol0+NH4OH200 mL×0.1M=20 mmol10→NH4Cl010 mmol+H2O
This is basic buffer.
HCl4) 100 mL×0.1 M=10 mmol0+NaOH100 mL×0.1 M=20 mmol0→NaCl010 mmol+H2O
Neutral solution.