Alkali metals dissolve in liquid ammonia giving deep blue solutions which are conducting in nature. The blue colour of the solution is due to ammoniated electrons which absorb energy in the visible region of light.

**Characteristics of the blue solution of sodium in liquid ammonia**

The blue solution of sodium in liquid ammonia is a unique system that exhibits several interesting properties. Let's discuss each characteristic in detail:

**a) Diamagnetic:**
The blue solution of sodium in liquid ammonia is diamagnetic. Diamagnetic substances are those that have all their electrons paired up in their respective orbitals, resulting in a net magnetic moment of zero. In this case, the blue color arises due to the presence of solvated electrons (e⁻(NH₃)ₙ), which are formed when sodium metal dissolves in liquid ammonia. These solvated electrons are diamagnetic in nature.

**b) Paramagnetic:**
Contrary to option 'a', the blue solution of sodium in liquid ammonia is actually paramagnetic. Paramagnetic substances have unpaired electrons in their orbitals, resulting in a net magnetic moment greater than zero. In this case, the solvated electrons in the blue solution of sodium in liquid ammonia are actually paramagnetic. The unpaired electron(s) present in the solvated electrons make the system paramagnetic and able to be attracted by an external magnetic field.

**c) Reducing in nature:**
The blue solution of sodium in liquid ammonia is a strong reducing agent. The solvated electrons present in the solution are highly reactive and can easily donate electrons to other species. This property makes the solution reducing in nature. It can be used as a powerful reducing agent in various chemical reactions.

**d) Conducts electricity:**
The blue solution of sodium in liquid ammonia is a good conductor of electricity. The solvated electrons act as charge carriers and can move freely through the solution, allowing for the conduction of electric current. This property is useful in applications such as electrolysis and the synthesis of organic compounds.

In summary, the correct answer is option 'B, C, D'. The blue solution of sodium in liquid ammonia is paramagnetic, reducing in nature, and conducts electricity.