# A mole of helium gas contains 6.02 x 10^{23} helium atoms. How many helium atoms are there in a...

## Question:

A mole of helium gas contains {eq}6.02 \times 10^{23} {/eq} helium atoms. How many helium atoms are there in a millimole of helium?

## Number of Atoms:

According to the given information, we'll convert the unit of the obtained value using the general relation shown below:

• {eq}\displaystyle 1\ mole= 1000\ millimoles {/eq}

After that, we'll substitute the above value in the given expression.

The value of the number of atoms of helium gas is:

{eq}1\ mol = 6.02 \times 10^{23}\ atoms {/eq}

Substituting {eq}1000\ millimoles {/eq} for {eq}1\ mol {/eq} in the above expression and simplifying it, we get:

{eq}\begin{align*} \displaystyle \rm 1000\ millimoles& = \rm 6.02 \times 10^{23}\ atoms \\ \displaystyle \rm 1\ millimoles& = \rm \frac{6.02 \times 10^{23}}{1000}\ atoms \\ & = \rm 6.02 \times 10^{23}\times 10^{-3}\ atoms \\ & = \rm 6.02 \times 10^{23-3}\ atoms \\ & =\boxed{\rm 6.02 \times 10^{20}\ atoms} \\ \end{align*} {/eq}