What is the average mass of a single chlorine atom in grams?

Answers I tried and failed:

70

2.13x10^25

5.88x10^23

1.178x10^-22

2.13x10^-21

Answer: m = 5.81x10-²³ g Cl

Explanation: First is to find the number of moles of Cl in 1 atom of Chlorine. To solve this we will use the Avogadro's Number to convert atoms to moles.

1 atom Cl x 1 mole Cl / 6.022x10²³ atoms Cl

= 1.66x10-²⁴ moles Cl

The next step is to convert the moles of Cl to mass using its molar mass.

1.66x10-²⁴ moles Cl x 35 g Cl / 1 mole Cl

= 5.81x10-²³ g Cl.

Cancel out the units of moles Cl.

It's 5.88 x 10^-23 ...