Question

How many moles of nitrogen are found in 3.497 x 1020 molecules of Cu(NO3)2?​

Answer 1

1.161 * $10^{-3}$ moles of nitrogen

Explanation:

Each cupric nitrate  Cu(NO3)2 molecule will contain 2 atoms of Nitrogen

Given that there are  3.497 x $10^{20}$ molecules of Cu(NO3)2

So there are 2 * 3.497 x $10^{20}$  atoms of nitrogen in 3.497 x $10^{20}$ molecules of Cu(NO3)2

One mole of nitrogen will contain 6.022 x $10^{23}$ ( this is the Avogadro number) atoms .

There fore in  2 * 3.497 x $10^{20}$ atoms we have 2*3.497 x $10^{20}$ /6.022 x $10^{23}$ moles of nitrogen

Simplifying this , there are 1.161 * $10^{-3}$ moles of nitrogen