Question

Arrange them in the increasing order of their of their solubility in water:
$NaCl$ , $MgO$ , $MgC{l}_2$

• A. $NaCl$ , $MgC{l}_2$ , $MgO$
• B. $MgO$ , $MgC{l}_2$ , $NaCl$
• C. $MgC{l}_2$ , $NaCl$ , $MgO$
• D. none of these

Answer 1

The correct option is B $MgO$ , $MgC{l}_2$ , $NaCl$

The more the lattice entalphy the less will be the ability to dissolve in water.

Lattice enthalpy is a measure of the strength of the forces between the ions in an ionic solid. The greater the lattice enthalpy, the stronger the forces.

Lattice enthalpy of $NaCl$ = 787kJ/mol

Lattice enthalpy of $Mg{Cl}_2$=+2534kJ/mol

Lattice enthalpy of $MgO$ = 3826kJ/mol

Since Lattice enthalpy is inversely proportional to solubility option B is correct.