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 conducti

Question

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 due to the ammoniated 
cation, [M(NH3)x]+ as well as the ammoniated electron, -, values of x and y 
depend on the extent of solvation by NH3. Dilute solutions are paramagnetic due 
to free ammoniated electrons.

Prashant Kotian · Accepted Answer

Correct answer: C. Step 1: Down the group of alkali metals (Group 1), the nuclear charge increases, but the number of electron shells also increases. Step 2: The addition of new electron shells causes the valence electrons to be located further from the nucleus, which leads to a decrease in first ionization energy, electronegativity, and the hydration energy of the univalent cations. Step 3: Conversely, the atomic and ionic radii systematically increase down the group. Therefore, atomic radius increases with increasing atomic number, matching option (d).

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