\(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(n_{Fe}=n_{H_2}=\dfrac{3.36}{22.4}=0.15\left(mol\right)\)
\(\Rightarrow m_{Fe}=0.15\cdot56=8.4\left(g\right)\)
\(m_{Cu}=m_{hh}-m_{Fe}=15-8.4=6.6\left(g\right)\)
\(n_{HCl}=2n_{H_2}=0.15\cdot2=0.3\left(mol\right)\)
\(C_{M_{HCl}}=\dfrac{0.3}{0.2}=1.5\left(M\right)\)