Question

if the average atomic mass of an element having two isotopes is 71, the ratio of the natural abundance of two isotopes of mass 70 and 74 will be ​

Answer 1

Let the abundance of isotope of mass 70 be x %.
abundance of isotope of mass 74 = (100- x) %.

atomic weight = $\frac{70 \times x+ (100-x) \times 74}{100}$

$\Rightarrow 71 = \frac{70x+ 7400 - 74x}{100}\\ \\ \Rightarrow 7100 = 70x+ 7400 - 74x\\ \\\Rightarrow -4x = -300\\ \\\Rightarrow x = 75$

Abundance of isotope with mass 70 is 75% and abundance of isotope with mass 74 is 25% .

Answer 2

Answer:75%

Explanation:aam=m1x+m2(100

-x)

/100

Substituiting m1 as 70 and m2 as 74 and aam as 71 in the above formula we get 75%