For $$\mathrm{NaCl}_{(\mathrm{s})}$$ enthalpy of solution is $$4 \mathrm{~kJ} \mathrm{~mol}^{-1}$$ and lattice enthalpy is $$790 \mathrm{~kJ} \mathrm{~mol}^{-1}$$. What is hydration enthalpy of $$\mathrm{NaCl}$$ ?

Which from following statements regarding transition elements is NOT CORRECT?

A solution of $$8 \mathrm{~g}$$ of certain organic compound in $$2 ~\mathrm{dm}^3$$ water develops osmotic pressure $$0.6 \mathrm{~atm}$$ at $$300 \mathrm{~K}$$. Calculate the molar mass of compound. [R = 0.082 atm dm$$^3$$ K$$^{-1}$$ mol$$^{-1}$$]

What is the value of $$\Delta H-\Delta U$$ for the following reaction?

$$2 \mathrm{C}_{(\mathrm{s})}+3 \mathrm{H}_{2(\mathrm{~g})} \rightarrow \mathrm{C}_2 \mathrm{H}_{6(\mathrm{~g})}$$