a) Đặt CTTQ của khí halogen cần tìm là X2
PTHH: \(Ca+X_2\xrightarrow[]{t^o}CaX_2\)
b)
\(n_{X_2}=\dfrac{18,5925}{24,79}=0,75\left(mol\right)\)
Theo PT: \(n_{CaX_2}=n_{X_2}=0,75\left(mol\right)\)
\(\Rightarrow M_{CaX_2}=\dfrac{82,35}{0,75}=111\left(g/mol\right)\)
\(\Rightarrow M_X=\dfrac{111-40}{2}=35,5\left(g/mol\right)\\ \Rightarrow X:Cl;X_2:Cl_2\)