Question

part b
2.60×10²² he atoms
express your answer using three significant figures.
ν =
mol

Explanation:

Step1: Recall Avogadro's number

Avogadro's number is $N_A = 6.022\times10^{23}\ \text{atoms/mol}$. To find the number of moles ($
u$), we use the formula $
u=\frac{N}{N_A}$, where $N$ is the number of atoms.

Step2: Substitute the values

Given $N = 2.60\times10^{22}\ \text{He atoms}$ and $N_A = 6.022\times10^{23}\ \text{atoms/mol}$. Substitute into the formula: $
u=\frac{2.60\times10^{22}}{6.022\times10^{23}}$.

Step3: Perform the calculation

First, simplify the exponents: $\frac{2.60}{6.022}\times\frac{10^{22}}{10^{23}}=\frac{2.60}{6.022}\times10^{-1}$. Calculate $\frac{2.60}{6.022}\approx0.4317$, then multiply by $10^{-1}$: $0.4317\times10^{-1}=0.04317$. Rounding to three significant figures gives $0.0432$ (or $4.32\times10^{-2}$).

Answer:

$0.0432$ (or $4.32\times10^{-2}$)