Question

DJ
35.
The percentage abundances of 12, 14 are 75% and 25% respectively. The
average atomic mass of carbon (in amu) is
A) 12.4
B) 12.3
C) 12.5
D) 12​

Answer 1

Isotopic Abundance of C-12 = 75%

Isotopic Abundance of C-14 = 25%

Average Atomic Mass = (75*12)+(25*14)/100

= 900+350/100

= 12.5 amu

I hope this helps.