A transitional metal `X^(+2)` in its hydrated state has six 3d electrons. The colour of ion is expected as

Options

A. Green
B. Pink
C. Blue
D. Yellow

Answer

To determine the expected color of the transition metal ion \( X^{2+} \) with six 3d electrons in its hydrated state, we can follow these steps:

### Step 1: Identify the electronic configuration of the ion
- Since \( X^{2+} \) has six 3d electrons, we first need to write the electronic configuration of the neutral atom \( X \).
- The neutral atom will have two additional electrons compared to the \( X^{2+} \) ion, which means it will have a total of 8 3d electrons (6 in 3d and 2 in 4s).
- The electronic configuration of \( X \) can be written as:
\[ [Ar] \, 3d^6 \, 4s^2 \]

### Step 2: Determine the atomic number of the metal
- The atomic number of the element can be calculated by adding the number of electrons in the configuration:
- Argon (Ar) has an atomic number of 18.
- Therefore, the total atomic number of \( X \) is:
\[ 18 + 6 + 2 = 26 \]
- Thus, \( X \) corresponds to iron (Fe), which has an atomic number of 26.

### Step 3: Identify the oxidation state and color of the ion
- In the \( +2 \) oxidation state, the electronic configuration of \( Fe^{2+} \) will be:
\[ [Ar] \, 3d^6 \, 4s^0 \]
- The presence of 6 electrons in the 3d subshell indicates that this ion can exhibit color due to d-d transitions.

### Step 4: Determine the expected color of \( Fe^{2+} \)
- The color of \( Fe^{2+} \) in its hydrated state is known to be light green.
- Therefore, the expected color of the ion \( X^{2+} \) is light green.

### Final Answer
The color of the ion \( X^{2+} \) is expected to be **light green**.

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