Which from following is a correct decreasing order of ionisation enthalpy for different elements?

Which among the following salts exhibits inverse relation between it's solubility and temperature?

Which from following series of elements is correctly arranged according to their decreasing order of ionisation enthalpy $$\left(\mathrm{IE}_1\right)$$ ?

Identify the product formed by the action of $$\mathrm{H}_2(\mathrm{~g})$$ with $$\mathrm{CO}(\mathrm{g})$$ in presence of $$\mathrm{Ni}$$ ?