Please solve for Cu, N,and O an dif you can show how cause ik confused

Cu⇒ 1 atom

N⇒2 atoms

O⇒6 atoms

Total 9 atoms

The empirical formula is the smallest comparison of atoms of compound forming elements.  

A molecular formula is a formula that shows the number of atomic elements that make up a compound.  

(empirical formula) n = molecular formula  

Chemical formula : Cu(NO₃)₂

Number of Cu : 1

Number of N : 2

Number of O = 2 x 3 = 6

Total atoms in Cu(NO₃)₂ : 1 + 2 + 6 = 9

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).