Q2)Calculate the percentage of copper in a sample of CuCl2 (atomic mass of Cu=63.5u Cl=35.5u)

Molar mass of CuCl₂  =  134.5g/mol
Mass percent of Cu in CuCl₂  = $\frac{{\text{mass of Cu in CuCl}}_2}{{\text{molar mass of CuCl}}_2}\times 100$
Substituting the values,

Mass percent of Cu in CuCl₂ = $\frac{63.5}{134.5}\times 100$ =  47.2%