The alkali metals dissolve in ammonia to give a deep blue solution which is cnducting in nature.
`M+(x+y)NH_(3)to[M(NH_(3))_(x)]^(2+)+2[e(NH_(3))_(y)]^(-)` which of the followin is not true about the solutions of alkali metals in liquid ammonia?

Options

A. The blue colour is due to ammoniated electron
B. the solution is paramagnetic.
C. The blue colour changes to brown on standing
D. In concentrated solution blue colour changes to bronze and becomes diamagnetic

Answer

To solve the question regarding the properties of alkali metals in liquid ammonia, let's break down the information step by step.

### Step 1: Understanding the Reaction
The reaction given is:
\[ M^+ + (x+y)NH_3 \rightarrow [M(NH_3)_x]^{2+} + 2[e(NH_3)_y]^{-} \]
This indicates that alkali metals (M) dissolve in ammonia (NH3) to form ammoniated cations and ammoniated electrons.

**Hint:** Identify the components of the reaction and what they represent.

### Step 2: Properties of the Solution
When alkali metals dissolve in ammonia, they produce a deep blue solution. This color is due to the presence of ammoniated electrons, which are responsible for the blue color of the solution.

**Hint:** Recall the role of ammoniated electrons in the coloration of the solution.

### Step 3: Conductivity of the Solution
The solution is conducting in nature because both the ammoniated cations and the ammoniated electrons contribute to the conductivity. The presence of free-moving charged particles allows the solution to conduct electricity.

**Hint:** Consider how ions and electrons contribute to electrical conductivity.

### Step 4: Changes Over Time
As the solution stands, it undergoes changes:
- It slowly liberates hydrogen gas.
- The solution changes from paramagnetic (due to unpaired electrons) to diamagnetic (due to paired electrons).
- The color changes from blue to bronze.

**Hint:** Think about the implications of paramagnetism and diamagnetism in relation to electron pairing.

### Step 5: Evaluating the Statements
Now, we need to evaluate the given statements to find the one that is not true:
- **A:** The blue color is due to ammoniated electrons. (True)
- **B:** The solution is paramagnetic. (True)
- **C:** The blue color changes to brown on standing. (Not true; it changes to bronze.)
- **D:** In concentrated solution, the blue color changes to bronze and becomes diamagnetic. (True)

**Hint:** Compare each statement with the information gathered from the previous steps.

### Conclusion
The statement that is not true about the solutions of alkali metals in liquid ammonia is:
**C:** The blue color changes to brown on standing.