Answer:
14.68 moles of He
Explanation:
To do this, just remember Avogadro's Constant or Avogadro's number. This constant tells us how many units ( in this case atoms) there are in a mole of ANY type of substance.
Avogadro's constant is 6.022140857 × 10²³ units per mole.
Now that we know how many atoms there are in 1 mole, we can use this as our conversion factor.
8.84 x 10²⁴ atoms of He → moles of He

So the answer would be:
14.68 moles of He
the answer is magnetic separation, not sedimentation separation
The answer to this question would be:
NCl3 is a molecular compound (two or more nonmetals), and therefore in its name prefixes indicate the number of each type of atom. so NCl3 is nitrogen trichloride<span>.
</span><span>The compound AlCl3 is an ionic compound (metal and nonmetal), and therefore does not require prefixes. so AlCl3 is aluminum chloride.
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Both of nitrogen and chlorine is nonmetal, but aluminum is metal. Metal with nonmetal will make an ionic compound that doesn't need prefixes.</span>