$298 \ K$ તાપમાને નીચેનામાંથી કયા મિશ્રણનો $pH$ સૌથી ઓછો હશે?

• A
  $10 \ mL$ $0.05 \ N$ $CH_{3}COOH + 5 \ mL$ $0.1 \ N$ $NH_{4}OH$
• B
  $5 \ mL$ $0.2 \ N$ $NH_{4}Cl + 5 \ mL$ $0.2 \ N$ $NH_{4}OH$
• C
  $5 \ mL$ $0.1 \ N$ $CH_{3}COOH + 10 \ mL$ $0.05 \ N$ $CH_{3}COONa$
• D
  $5 \ mL$ $0.1 \ N$ $CH_{3}COOH + 5 \ mL$ $0.1 \ N$ $NaOH$