a) PTHH: \(MgCl_2+2NaOH\rightarrow Mg\left(OH\right)_2\downarrow+2NaCl\)
\(Mg\left(OH\right)_2\underrightarrow{t^O}MgO+H_2O\)
b) Ta có: \(n_{MgCl_2}=0,2\cdot0,15=0,3\left(mol\right)\)
\(\Rightarrow n_{Mg\left(OH\right)_2}=0,3mol=n_{MgO}\) \(\Rightarrow m_{MgO}=0,3\cdot40=12\left(g\right)\)
c) Theo PTHH: \(n_{NaCl}=2n_{MgCl_2}=0,6mol\)
\(\Rightarrow C_{M_{NaCl}}=\frac{0,6}{0,2+0,3}=1,2\left(M\right)\)