Question

G. The natural isotopic abundance of lºB
is 19.60% and 11B is 80.40%. The exact
isotopic masses are 10.13 and 11.009
respectively. Calculate the average
atomic mass of boron
(Ans. :10.81)
​

Answer 1

Answer:

From the question we get that the relative abundance of 10B isotope of boron is =  19.60%.

Also, the relative abundance of 11B isotope of boron is  = 80.40%.

Since, we know that the formulae of average atomic mass is (Mass of first isotope) x (Relative abundance of 10B isotope)  + (Mass of second isotope) x (Relative abundance of 11B isotope) / 100.

So, on putting the value we will get that:-

= (10 x 19 ) + (11 x 81 ) / 100.

= 190 + 891 / 100.

= 1081/100.

Which on solving we will get that 10.81 u.

Therefore, the average atomic mass of boron we will get is 10.81 u.

Explanation:

please do follow me