# Question #2d508

Jun 21, 2017

#### Answer:

The percentage of $\text{N-14}$ is 99.6 %.

#### Explanation:

The masses of $\text{N-14}$ and $\text{N-15}$ are 14.003 u and 15.000 u, respectively.

Let $x$ be the fraction of $\text{N}$ that is $\text{N-14}$.

Then $\left(1 - x\right)$ is the fraction that is N-15.

$14.003 x \textcolor{red}{\cancel{\textcolor{b l a c k}{\text{u"))) + (1-x) color(red)(cancel(color(black)("u"))) = 14.007 color(red)(cancel(color(black)("u}}}}$

$14.003 x + 15.000 - 15.000 x = 14.007$

$0.997 x = 0.993$

$x = \frac{0.993}{0.997} = 0.996$

∴ Natural nitrogen is 99.6 % $\text{N-14}$.