Please teach me this whole page of questions (1-4) questions (1-5) thank u very much

1. Calculate the pH of a buffer solution that contains 0.25M benzoic acid (C6H5CO2H) and 0.15M sodium benzoate (C6H3COONa). [K2=6.5105 for benzoic acid] A) 3.97 B) 4.83 c) 4.19 D) 3.40 E) 4.41 2. A solution is prepared by mixing 500 . mL of 0.10MNaOCl and 500.mL of 0.20 M HOCl. What is the pH of this solution? [K2(HOCl)=3.2101] A) 4.10 B) 7,00 C) 7.19 D) 7.49 E) 7.80 3. Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 9.29.3 ? A) CH3COONa/CH3COOH(K2=1.8105) B) NH3/NH4Cl(K2=5.6+1010) C) NaOC/HOCl(K3=3.2,104) D) NaNO2/HNO2(Ke=4.5104) E) NaCl/HCl 4. What mass of ammonium nitrate must be added to 350 . mL of a 0.150M solution of ammonia to give a buffer having a pH of 9.00?(K2(NH3)=1.8105) A) 7.6B B) 2.4g C) 5.4B D) 11g E) 3.38 Quesetion 1. Which one of the following is a buffer solution? A) 0.40MHCN and 0.10KCN D) 0.10MKCN B) 0.20MCH3COOH E) 0.50MHCl and 0.10NaCl C) 1.0MHNO3 and 1.0MNaNO3 2. Which one of the following combinations cannot function as a buffer solution? A) HCN and KCN D) HF and NaF B) NH3 and (NH4)2SO4 E) HNO2 and NaNO2 C) HNO3 and NaNO3 3. Calculate the pH of a buffer solution that contains 0.25M benzoic acid (C2H3CO2H) and 0.15M sodium benzoate (C2H5COONa).[K2=6.5105 for benzoic acid] A) 3.97 B) 4.83 C) 4.19 D) 3.40 E) 4.41 4. Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of cyanic acid (HCNO) and 0.80 mole of sodium cyanate (NaCNO) in enough water to make 1.0 liter of solution. [KN(HCNO)=2.0104] A) 0.97 B) 3.10 C) 4.40 D) 3.70 E) 4.30 5. You have 500.0mL of a buffer solution containing 0.20M acetic acid (CH3COOH) and 0.30M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00MNaOH solution? [Ka=1.8105] A) 4.41 B) 4.74 D) 4.92 (b) 5.07