Lol it's quite simple to start a new thread but anyway.
As the curve will be linear or close to it, we can say \frac{[Cu^{2+}]}{0.500}=\frac{10 ppm}{0.400}
\therefore Cu^{2+}=12.5 ppm which equals 12.5 mg/L
therefore Cu2+ in 100 mL is 1/10x12.5=1.25 mg
number of moles of Cu2+= 0.00125/65.55 =...