Question

is magnesium oxide soluble in water ? if no how it forms magnesium hydroxide n if yes why only sodium oxide n potassium oxide is considered to be soluble in water as per NCERT CLASS 10 science .....PLZ HELP ME....

Answer 1

MgO is sparingly soluble in water .

here MgO have high lattice enthalpy  it means ( strong bond )

it means that small amount MgO dissolved and convert into Mg(OH)₂ 
 
here the lattice enthalpy is lesser then hydration enthalpy 

Potassium,and Sodium and  oxides react vigorously with water  to form 

KOH and NaOH ...