Question

moles of Cu in 7.8 * 10^21 atoms of Cu

Answer 1

n(Cu) = 7.8x10^21/6.02x10^23
n(Cu)=0.013moles of copper

Answer 2

Explanation:

According to mole concept, 1 mole of every substance contains $6.02 \times 10^{23}$ atoms or molecules.

As number of atoms present in given copper are $7.8 \times 10^{21}$ atoms. Therefore, calculate the number of moles present in this copper atom as follows.

       No.of moles = $\frac{7.8 \times 10^{21}}{6.02 \times 10^{23}}$

                            = $1.29 \times 10^{-2}$

                            = 0.0129 mol

Thus, we can conclude that there are 0.0129 moles of copper present in $7.8 \times 10^{21}$ atoms.