Question

which of the following contains the most moles of atoms? answer: a 1 g of helium b 1 g of carbon c 1 g of uranium d all contain equal number of atoms.

Explanation:

Step1: Recall mole - mass formula

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

Step2: Find molar masses

The molar mass of helium $M_{He}=4\ g/mol$, carbon $M_{C} = 12\ g/mol$, uranium $M_{U}=238\ g/mol$.

Step3: Calculate moles for each

For helium, $n_{He}=\frac{1\ g}{4\ g/mol}=0.25\ mol$. For carbon, $n_{C}=\frac{1\ g}{12\ g/mol}\approx0.083\ mol$. For uranium, $n_{U}=\frac{1\ g}{238\ g/mol}\approx0.0042\ mol$.

Answer:

A. 1 g of helium