The atomic mass of fluorine is 19.00 amu, and all fluorine atoms in a naturally occurring sample of fluorine have this mass. The atomic mass of chlorine is 35.45 amu, but no chlorine atoms in a naturally occurring sample of chlorine have this mass Provide an explanation for the difference. Check alt that apply A. Fluorine has three isotopes with atomic masses 18.00 amu, 19.00 amu and 20.00 amu, and their appearance in nature is equal, while the appearance of chlorine is not equal.
B. Chlorine has more than one stable isotope that occurs naturally.
C. Chlorine does not exist as an elemental part, there is chlorine gas with two different chlorine atoms that results the atomic mass 35.45 amu.
D. As fluorine only has one isotope the atomic mass is identical to the mass of the isotope.

B. Chlorine has more than one stable isotope that occurs naturally.

D. As fluorine only has one isotope the atomic mass is identical to the mass of the isotope.

Explanation:

The reason for the difference seen between the atomic mass provided in the periodic table and the atomic mass of each element is that most naturally occurring elements have more than one isotope (isotopes are atoms that have the same atomic number but different mass numbers). This means that when we measure the atomic mass of an element, we must generally settle for the average mass of the naturally occurring mixture of isotopes.

¹⁹F is the only stable isotope of fluorine, and its abundance is 100%. Therefore, its atomic mass is identical to that of the isotope.

On the other hand, chlorine has two stable isotopes ³⁵Cl (75.77%) and ³⁷Cl (24.23%). The atomic mass of  ³⁵Cl has been determined to be 34.96885 amu, and the atomic mass of ³⁷Cl has been determined to be 36.96590 amu. Thus, the average atomic mass  of chlorine can be calculated as follows:

average atomic mass  of natural chlorine = (0.7577)×(34.96885 amu) + (0.2423)×(36.96590 amu)  = 35.45 amu

Note that in calculations involving percentages, we need to convert percentages to  fractions.