The ionic radii of alkali metal ions in aqueous solution follows the order Li⁺ > Na⁺> K⁺ > Rb⁺ > Cs⁺ Justify the above order.

Discuss the general trends in ionisation enthalpy and electropositive character of alkali metals.

Why do alkali metals impart characteristic colours to the flame?

Why do alkali metals from unipositive ions?

Lithium 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.

Explain why alkali metals are electrically conducting and form soluble salts ?

How will you explain that alkali metals are chemically highly receive?

Why are potassium and caesium, rather than lithium used in photoelectric cells?

How will you explain that alkali metals are strong reducing agents?