Please help So I did a titration lab for the purpose of determining the concentration of Ag in the solution. As I was doing the titration, I think I exceeded the end point because a precipitate formed at the top of the solution and the color of solution turned reddish brown. I'm not sure what law/concept/or principle I can use to describe how or why this happened.

the right answer is c i just did the question.

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally