Short Answer TypeThe ionic radii of alkali metal ions in aqueous solution follows the order Li+ > Na+> K+ > Rb+ > Cs+ Justify the above order.
Long Answer TypeDiscuss the general trends in ionisation enthalpy and electropositive character of alkali metals.
Short Answer TypeLithium ion has the lowest and caesium ion has the highest mobility in an electric field. Explain.
When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reactions for this type of colour change.
Or
Explain why alkali metals dissolve in liquid ammonia to form deep blue solution.
How will you explain that alkali metals are strong reducing agents?
Lower the ionisation enthalpy, greater is the tendency of an element to lose electrons and hence stronger is the reducing character or higher is the reactivity of the element. Since the ionisation enthalpies of alkali metals decrease down the group, therefore, their reducing character or reactivity in the gaseous state increases from Li to Cs i.e. Li < Na < K < Rb < Cs. However, in the aqueous solution, it has been absorbed that the reducing character of alkali metals follows the sequence Na < K < Rb < Cs < Li. In other words, lithium is the strongest reducing agent in aqueous solution.
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