Carbon occurs in nature as a mixture of 12C and 13C. The average atomic mass of carbon is 12.011. What is the % abundance of 12C in nature?

Question

Carbon occurs in nature as a mixture of 12C and 13C. The average atomic mass of carbon is 12.011. What is the % abundance of 12C in nature? (A) 89 % (B) 98.9 % (C) 89.9 % (D) 79.9 %

Tardigrade Admin · Accepted Answer

Let % abundance of 12C = x % abundance of 13C =100-x ∵ (12x/100) +(13(100-x)/100) = 12.011 12x+1300-13x= 1201.1 ⇒ x=98.9 Thus, % abundance of 12C is 98.9 %

Q. Carbon occurs in nature as a mixture of $^{12} C$ and $^{13} C$ . The average atomic mass of carbon is $12.011$ . What is the $%$ abundance of $^{12} C$ in nature?

$89%$

$98.9%$

$89.9%$

$79.9%$

Let $%$ abundance of $^{12} C = x$
$%$ abundance of $^{13} C = 100 - x$
$∵ \frac{12 x}{100} + \frac{13 ( 100 - x )}{100} = 12.011$
$12 x + 1300 - 13 x = 1201.1$
$\Rightarrow x = 98.9$
Thus, $%$ abundance of $^{12} C$ is $98.9%$

Q. Carbon occurs in nature as a mixture of 12C and 13C. The average atomic mass of carbon is 12.011. What is the % abundance of 12C in nature?

89%

98.9%

89.9%

79.9%