the number of d electrons is `Co` is equal to that of

Options

A. s and p electrons in F atom
B. p electrons in Ar
C. d electrons in `Co^(2+)`
D. Total No. of electron in N atom

Answer

To determine the number of d electrons in cobalt (Co) and find an element with an equal number of d electrons, we can follow these steps:

### Step 1: Determine the electronic configuration of cobalt (Co).
Cobalt has an atomic number of 27. Its electronic configuration is:
\[ \text{Co: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7 \]

### Step 2: Identify the number of d electrons in cobalt.
From the electronic configuration, we can see that cobalt has 7 electrons in the 3d subshell. Therefore, the number of d electrons in cobalt is:
\[ \text{Number of d electrons in Co} = 7 \]

### Step 3: Find another element with the same number of d electrons.
We need to find another element that has 7 d electrons. We can look at transition metals in the periodic table.

- For example, Nickel (Ni) has an atomic number of 28 and its electronic configuration is:
\[ \text{Ni: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8 \]
This has 8 d electrons, which is not equal to 7.

- Next, we can check Manganese (Mn) which has an atomic number of 25:
\[ \text{Mn: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^5 \]
This has 5 d electrons, which is also not equal to 7.

- Finally, we can check Iron (Fe) which has an atomic number of 26:
\[ \text{Fe: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6 \]
This has 6 d electrons, which is still not equal to 7.

### Step 4: Conclusion
The only element that has the same number of d electrons as cobalt (7 d electrons) is cobalt itself in its +2 oxidation state (Co²⁺), which retains 7 d electrons after losing 2 electrons from the 4s subshell.

### Final Answer
The number of d electrons in cobalt (Co) is equal to that of cobalt in its +2 oxidation state (Co²⁺).

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