Problem- A) For 490.0mL of pure water, calculate the initial pH and the final pH after adding 0.020mol of HCl. Express your answers using two decimal places separated by a comma.
B) For 490.0mL of a buffer solution that is 0.165M in HC2H3O2 and 0.155M in NaC2H3O2, calculate the initial pH and the final pH after adding 0.020mol of HCl.
C) For 490.0mL of a buffer solution that is 0.185M in CH3CH2NH2 and 0.175M in CH3CH2NH3Cl, calculate the initial pH and the final pH after adding 0.020mol of HCl.
Please explain above problem in step by step manner so I can easily understand it