How many moles of H+(aq) ions are present in 750 mL of 0.65 M hydrochloric acid?

n (moles) = C (concentration) x V (volume in L)

n = 0.65 x 0.75

n = 0.4875 moles of HCl

HCl is a strong acid so it pretty much totally ionises so there are as many H+(aq) ions as there is HClHCl ==> H + Cl  

Explanation:

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