What is the pH of a buffer formed by adding 0.53 g of sodium benzoate, NaC6H5COO (molar mass = 144.1 g/mol ) to 290 mL of a 0.43 M solution of benzoic acid, C6H5COOH ( Ka=6.3×10−5 )? Neglect any changes in volume that occur upon adding the salt. 5.73 2.67 4.29 4.20