<p>The ionisation energy of solid NaCl is 180 kcal per mol. The dissolution of the solid in water in the form of ions is endothermic to the extent of 1 kcal per mol. If the solvation energies of&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mi>N</mi><msup><mi>a</mi><mo>+</mo></msup><mo>&#160;</mo><mi>a</mi><mi>n</mi><mi>d</mi><mo>&#160;</mo><mi>C</mi><msup><mi>l</mi><mo>-</mo></msup></math>&nbsp;ions are in the ratio 6 : 5, what is the enthalpy of hydrogen of sodium ion?</p>