Answer :

Final answer:

The relative formula mass of chlorine is 35.5 because chlorine has isotopes with different mass numbers.


Explanation:

The relative formula mass of chlorine is 35.5 because chlorine has two isotopes: chlorine-35 and chlorine-37. Isotopes are atoms of the same element with different mass numbers due to a different number of neutrons. The isotopes of chlorine exist in a ratio, with chlorine-35 being more abundant. The relative formula mass is calculated by taking the average mass of each isotope, weighted by its abundance, which results in a value that is not a whole number.


Learn more about Isotopes of chlorine here:

https://brainly.com/question/38714224