1. A hypothetical element consists of 3 isotopes
with the following masses and natural abundances.
Isotopic Natural
Mass Abundance
Number %
1 39 78.8
2 40 18.1
3 41 3.1
What is the atomic weight?
A. 40.9

B. 39.9

C. 39.2

D. 40.1

2. A hypothetical pure element consists entirely of two isotopes. The natural percent abundance of the isotope with mass 25.6 u is 51.7%.The other isotope has mass 29.8 u. Calculate the atomic weight of the naturally occurring element?

Question

1. A hypothetical element consists of 3 isotopes 
 with the following masses and natural abundances. 
 Isotopic Natural 
 Mass Abundance 
 Number % 
 1 39 78.8 
 2 40 18.1 
 3 41 3.1 
 What is the atomic weight? 
 A. 40.9 

 B. 39.9 

 C. 39.2 

 D. 40.1 

 2. A hypothetical pure element consists entirely of two isotopes. The natural percent abundance of the isotope with mass 25.6 u is 51.7%.The other isotope has mass 29.8 u. Calculate the atomic weight of the naturally occurring element?