The ratio of unpaired electrons present in d orbitals of `Co^(2+)` and `Cr^(3+)` is ______. 

Answer

To determine the ratio of unpaired electrons present in the d orbitals of Co²⁺ and Cr³⁺, we will follow these steps:

### Step 1: Determine the electronic configuration of Co²⁺
Cobalt (Co) has an atomic number of 27. The electronic configuration of neutral cobalt is:
\[ \text{Co: } [Ar] 3d^7 4s^2 \]

When cobalt loses 2 electrons to form Co²⁺, it loses the 4s electrons first. Therefore, the electronic configuration of Co²⁺ is:
\[ \text{Co}^{2+}: [Ar] 3d^7 \]

### Step 2: Determine the distribution of electrons in the d orbitals for Co²⁺
In the 3d subshell, the 7 electrons will be distributed as follows:
- The 3d orbitals can hold a maximum of 10 electrons (5 orbitals).
- According to Hund's rule, we fill each orbital singly before pairing.

The distribution of 7 electrons in the 3d orbitals is:
- ↑ ↑ ↑ ↑ ↑ (5 electrons in 5 orbitals, singly occupied)
- ↑ ↑ (2 electrons, paired in two of the orbitals)

Thus, Co²⁺ has 3 unpaired electrons.

### Step 3: Determine the electronic configuration of Cr³⁺
Chromium (Cr) has an atomic number of 24. The electronic configuration of neutral chromium is:
\[ \text{Cr: } [Ar] 3d^5 4s^1 \]

When chromium loses 3 electrons to form Cr³⁺, it loses the 4s electron and two from the 3d subshell. Therefore, the electronic configuration of Cr³⁺ is:
\[ \text{Cr}^{3+}: [Ar] 3d^3 \]

### Step 4: Determine the distribution of electrons in the d orbitals for Cr³⁺
In the 3d subshell, the 3 electrons will be distributed as follows:
- ↑ ↑ ↑ (3 electrons, each occupying a separate orbital)

Thus, Cr³⁺ has 3 unpaired electrons.

### Step 5: Calculate the ratio of unpaired electrons
Now that we have the number of unpaired electrons:
- Co²⁺ has 3 unpaired electrons.
- Cr³⁺ has 3 unpaired electrons.

The ratio of unpaired electrons in Co²⁺ to Cr³⁺ is:
\[ \text{Ratio} = \frac{\text{Unpaired electrons in Co}^{2+}}{\text{Unpaired electrons in Cr}^{3+}} = \frac{3}{3} = 1 \]

### Final Answer
The ratio of unpaired electrons present in d orbitals of Co²⁺ and Cr³⁺ is **1**.

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