Solution :
The balanced equation is :
               [tex]$Ni^{2+}+2H_2C_4H_6O_2N_2 \rightarrow Ni(H_2C_4H_6O_2N_2)_2+2H^+$[/tex]
Molar mass      56.7       116             290.7
From the balanced equation,
2 mole
= 2 x 116 g of [tex]$H_2C_4H_6O_2N_2$[/tex] produces 1 mole = 290.7 g of nickel dimethylglycoxime
or 2 x 116 mg of [tex]$H_2C_4H_6O_2N_2$[/tex] produces 1 mole = 290.7 g of nickel dimethylglycoxime
0.175 mg of [tex]$H_2C_4H_6O_2N_2$[/tex] produces [tex]$\frac{0.175 \times 290.7}{2 \times 116}$[/tex] = 0.219 mg of nickel dimethylglycoxime
290.7 g of [tex]$Ni(H_2C_4H_6O_2N_2)_2$[/tex] contains 58.7 mg of Ni
0.219 mg of [tex]$Ni(H_2C_4H_6O_2N_2)_2$[/tex] contains [tex]$\frac{0.219 \times 58.7}{290.7} = 0.0443$[/tex] Â mg of Ni
So mass of nickel, m = 0.0443 mg = [tex]$0.0443 \times 10^{-3}$[/tex] g
Percent of Nickel in the alloy = [tex]$\frac{\text{mass of nickel}}{\text{mass of alloy}} \times 100$[/tex]
                        [tex]$=\frac{0.0443 \times 10^{-3}}{0.159}\times 100$[/tex]
                        = 0.03%