Question

An Element Of Atomic Mass M Consists Of Two Isotopes Of Mass Number M+1 &Amp;M+2 The Percentage Abundance Of Lighter Isotope Is

Answer 1

Hey Dear,

There's some error in the question. Average atomic mass can't be lesser than both lighter and heavier isotope. So we'll consider mass of lighter isotope as M-1. If there's something else, you can modify accordingly.

◆ Answer -

66.67 %

● Explaination -

Let x be percentage of lighter isotope. Then percentage of higher isotope is 100-x.

Average atomic mass of element is calculated as -

M = (M-1) × x/100 + (M+2) × (100-x)/100

100M = Mx - x + 100M + 200 - Mx - 2x

200 = 3x

x = 200/3

x = 66.67 %

Therefore, percentage abundance of lighter isotope must be 66.67 %.

Best luck...