Three isotopes of argon occur in nature – 36 18ar, 38 18ar, 40 18ar. calculate the average atomic mass of argon to two decimal places, given the following relative atomic masses and the abundances of each of the isotopes: argon36 (35.97 amu; 0.337%), argon-38 (37.96 amu; 0.063%), argon-40 (39.96 amu; 99.600%). 1. 119.89 amu 2. 39.95 amu 3. 39.96 amu 4. 35.97 amu 5. none of these 6. 37.96 amu 7. 37.95 amu 8. 35.96 amu

3) 39.96 amu

Explanation:

Mass of isotope Ar- 36 = 35.97 amu

% abundance of isotope Ar- 36= 0.337% =

Mass of isotope Ar- 38 = 37.96 amu

% abundance of isotope 2 = 0.063 % =

Mass of isotope Ar- 40 = 39.96 amu

% abundance of isotope 2 = 99.600 % =

Formula used for average atomic mass of an element :

Therefore, the average atomic mass of argon is 39.96 amu

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).