An element is found in nature in two isotopic forms with mass numbers (A-1) and (A + 3). If the average atomic mass of the element is found to be A, then the relative abundance of the heavier isotope in the nature will be.

Question

An element is found in nature in two isotopic forms with mass numbers (A-1) and (A + 3). If the average atomic mass of the element is found to be A, then the relative abundance of the heavier isotope in the nature will be. (A) 66.6 % (B) 75 % (C) 25 % (D) 33.3 %

Tardigrade Admin · Accepted Answer

Let relative abundance of heavier isotope be x % A=((100-x)(A-1)+x(A+3)/100) 100 A =100 A - xA -100+ x +3 x + xA 4 x=100 ∴ x=25

Q. An element is found in nature in two isotopic forms with mass numbers (A-1) and (A + 3). If the average atomic mass of the element is found to be $A$ , then the relative abundance of the heavier isotope in the nature will be.

$66.6%$

$75%$

$25%$

$33.3%$

Let relative abundance of heavier isotope be $x %$

$A = \frac{( 100 - x ) ( A - 1 ) + x ( A + 3 )}{100}$

$100 A = 100 A - x A - 100 + x + 3 x + x A$

$4 x = 100$

$∴ x = 25$

Q. An element is found in nature in two isotopic forms with mass numbers (A-1) and (A + 3). If the average atomic mass of the element is found to be A, then the relative abundance of the heavier isotope in the nature will be.

66.6%

75%

25%

33.3%