When an alkali metal dissolves in liquid ammonia the solution can acquire different colours. Explain the reasons for this type of colour change.

The alkali metals are soft in nature and this softness further increases down the group- Explain with reason.

All alkali metals dissolve in anhydrous liquid ammonia to give blue colour solution. It is the ammoniated electron which is responsible for the blue colour of the solution, and the electrical conductivity is mainly due to ammoniated electron, [e(NH_3)_y]^- Dilute solutions are paramagnetic due to free ammoniated electrons, this paramagnetism decreases at higher concentration. Above 3M concentration, the solutions are diamagnetic and no longer blue but are bronze/copper-bronze coloured with a metallic luster. Ammoniated solutions of alkali metals are reducing agents due to the :

Colloidal sols prepared by different methods differ in colour'-Explain with reason.

Why do some of the alkali metal salts impart colour to the flame?

Solution of sodium metals in liquid ammonia is strongly reducing due to the presence of :

In certain matters, lithium differs from other alkali metals, the main reason for this is :

Which alkali metal chloride imparts violet colour to the bunsen burner flame ?

What makes alkali metal halides sometimes coloured which are othersise colourless ?