\(\begin{array} {l} a)\\ Mg+2HCl\to MgCl_2+H_2\\ b)\\ n_{Mg}=\dfrac{7,2}{24}=0,3(mol)\\ \text{Theo PT: }n_{HCl}=2n_{Mg}=0,6(mol)\\ 500ml=0,5l\\ \to C_{M\,HCl}=\dfrac{0,6}{0,5}=1,2M\\ c)\\ n_{CuO}=\dfrac{16}{80}=0,2(mol)\\ \text{Theo PT: }n_{H_2}=n_{Mg}=0,3(mol)\\ CuO+H_2\xrightarrow{t^o}Cu+H_2O\\ \text{Vì }n_{CuO}<n_{H_2}\to H_2\text{ dư}\\ \text{Vậy lượng hiđro đủ để khử hết }16g\,CuO\end{array}\)