Vì : \(M\in IIA\Rightarrow M\text{Có hóa trị II}\)
\(M+2HCl\rightarrow MCL2+H2\uparrow\)
0,1.......0,2............0,1............0,1...........(mol)
\(\Rightarrow n_{H2}=\frac{V}{22,4}=\frac{2,24}{22,4}=0,1\left(mol\right)\)
\(M_M=\frac{m}{n}=\frac{n4}{0,1}=40\)
\(\Rightarrow M:Ca\)
b,Đổi 250ml=0,25l
\(\Rightarrow CM_{HCL}=\frac{0,2}{0,25}=0,8M\)