Question

An element P has two isotopes with relative abundance of 65% and 35%. If the mass number of the two isotopes is X and 31 respectively, find the mass number represented by X given that the relative atomic mass of element P is 30.

Answer 1

29.5

Step-by-step explanation:

Given parameters:

Abundance of P- 30 = 65% = 0.65

Abundance of P-31 = 35% = 0.35

Mass number of P-30 = X

Mass number of P - 31 = 31

Relative atomic mass of substance = 30

Unknown:

Mass number of P-30

Solution:

To solve this problem, apply the formula below;

R.A.M = (mass number of P-30 x Abundance of P-30) + (mass number of P-30 x abundance of P-31)

Now insert the parameters and solve for X;

30 = (X x 0.65) + (31 x 0.35)

30 = 0.65X + 10.85

30 - 10.85 = 0.65X

19.15 = 0.65X

X = 29.5