The first ionization enthalpy of Na, Mg and Si, respectively, are : 496, 737 and $$786 \mathrm{~kJ} \mathrm{~mol}^{-1}$$. The first ionization enthalpy ($$\mathrm{kJ} \,\mathrm{mol}^{-1}$$) of $$\mathrm{Al}$$ is :

The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives :

Number of lone pairs of electrons in the central atom of $$\mathrm{SCl}_{2}, \mathrm{O}_{3}, \mathrm{ClF}_{3}$$ and $$\mathrm{SF}_{6}$$, respectively, are :

In following pairs, the one in which both transition metal ions are colourless is :