Question

an element A has two isotopes A1 and A2 having mass number 35 and 37 respectively. the average atomic mass of A is found to be 35.5u then the percentage abundance of A1 and A2 respectively are​

Answer 1

Answer:

98 percent of A1 and 95 percent of A2

Answer 2

Given:

An element A has two isotopes A1 and A2 having mass number 35 and 37 respectively. the average atomic mass of A is found to be 35.5u.

To find:

The percentage abundance of A1 and A2.

Calculation:

Let % abundance of A1 be x% and that of A2 be (100-x)%.

$\therefore \: avg. \: mass = \dfrac{35x + 37(100 - x)}{100}$

$= > \: 35.5 = \dfrac{35x + 37(100 - x)}{100}$

$= > \: 3550 = 35x + 37(100 - x)$

$= > \: 3550 = 35x + 3700 - 37x$

$= > 2x = 3700 - 3550$

$= > 2x = 150$

$= > x = 75\%$

So, (100-x) = 25%.

So, final answer is:

$\boxed{ \bf{A1 = 75\% \: and \: A2 = 25\%}}$