Which one of the following statements regarding the oxides of alkali and alkaline earth metals is not correct ?
A. the reactivity of `K_(2)O` towards water is more than that of `Na_(2)O` towards water.
B. the oxides of alkaline earth metal are more basic than those of alkali metals
C. MgO is used as a refactory material for lining electric furnances.
D. the milk of lime and lime water are two different solutions.

Which one of the following statements regarding the oxides of alkali and alkaline earth metals is not correct ?
A. the reactivity of `K_(2)O` towards water is more than that of `Na_(2)O` towards water .
B. the oxides of alkaline earth metals are more basic than those of alkali metals .
C. MgO is used as a refractory material for lining electric furnaces .
D. the milk of lime and lime water are two different solutions .