the molar mass of helium, he, is 4.003 g/mol. how many moles of helium are in 8.57 g he? ? mol he

Explanation:

Step1: Recall mole - mass formula

The formula to calculate the number of moles $n$ is $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar mass.

Step2: Substitute given values

Given $m = 8.57\ g$ and $M=4.003\ g/mol$. Then $n=\frac{8.57}{4.003}$.

Step3: Calculate the result

$n\approx2.14\ mol$.

Answer:

$2.14$