A closed container has 2.04 ⋅ 1023 atoms of a gas. Each atom of the gas weighs 1.67 ⋅ 10−24 grams. Which of the following shows and explains the approximate total mass, in grams, of all the atoms of the gas in the container?

0.34 grams, because (2.04 ⋅ 1.67) ⋅ (1023 ⋅ 10−24) = 3.4068 ⋅ 10−1
0.37 grams, because (2.04 + 1.67) ⋅ (1023 ⋅ 10−24) = 3.71 ⋅ 10−1
3.41 grams, because (2.04 ⋅ 1.67) ⋅ (1023 ⋅ 10−24) = 3.4068
3.71 grams, because (2.04 + 1.67) ⋅ (1023 ⋅ 10−24) = 3.71

Question

A closed container has 2.04 ⋅ 1023 atoms of a gas. Each atom of the gas weighs 1.67 ⋅ 10−24 grams. Which of the following shows and explains the approximate total mass, in grams, of all the atoms of the gas in the container?

 0.34 grams, because (2.04 ⋅ 1.67) ⋅ (1023 ⋅ 10−24) = 3.4068 ⋅ 10−1
 0.37 grams, because (2.04 + 1.67) ⋅ (1023 ⋅ 10−24) = 3.71 ⋅ 10−1
 3.41 grams, because (2.04 ⋅ 1.67) ⋅ (1023 ⋅ 10−24) = 3.4068
 3.71 grams, because (2.04 + 1.67) ⋅ (1023 ⋅ 10−24) = 3.71

holsteremission · Answer

$$(2.04\times10^{23}\text{ atoms})\left(\frac{1.67\times10^{-24}\text{ grams}}{1\text{ atom}}\right)=\cdots\text{ grams}$$

paigephay_31903 · Answer

What? @HolsterEmission

holsteremission · Answer

That's the setup for this dimensional analysis. Multiplying x atoms by y grams per atom gives you a new quantity of z grams. See for example: https://www.chem.tamu.edu/class/fyp/mathrev/mr-da.html The next thing to do from here is to actually compute the quantity.