The atomic number of chromium is `24` Its electronic coefigueration in ground state in `1s^(2) 2s^(2)2p^(6)3s^(2)4s^(1) 3d^(5)` .Chromium atom by using `3` electron from `Cr ^(2+)` .A chromium atom contain `17%` morte neutron than the proton. Now answer the following questions
The number of occupied sub- shell in `Cr^(3+)` ion is

Options

A. 3
B. 4
C. 5
D. 6

Answer

To determine the number of occupied subshells in the Cr³⁺ ion, we will follow these steps:

### Step 1: Understand the Electronic Configuration of Chromium
The atomic number of chromium (Cr) is 24. Its ground state electronic configuration is:
\[ \text{Cr: } 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5 \]

### Step 2: Determine the Configuration of Cr³⁺
To find the electronic configuration of Cr³⁺, we need to remove three electrons from the ground state configuration of Cr. Electrons are removed from the outermost shell first, which in this case is the 4s subshell followed by the 3d subshell.

1. Remove 1 electron from the 4s subshell:
- From \(4s^1\), it becomes \(4s^0\).

2. Remove 2 electrons from the 3d subshell:
- From \(3d^5\), it becomes \(3d^3\).

Thus, the electronic configuration for Cr³⁺ is:
\[ \text{Cr}^{3+}: 1s^2 2s^2 2p^6 3s^2 3p^6 4s^0 3d^3 \]

### Step 3: Identify the Occupied Subshells
Now, we will identify the occupied subshells in the configuration of Cr³⁺:
- \(1s^2\) - occupied
- \(2s^2\) - occupied
- \(2p^6\) - occupied
- \(3s^2\) - occupied
- \(3p^6\) - occupied
- \(4s^0\) - not occupied
- \(3d^3\) - occupied

### Step 4: Count the Number of Occupied Subshells
The occupied subshells are:
- 1s
- 2s
- 2p
- 3s
- 3p
- 3d

Thus, the total number of occupied subshells in Cr³⁺ is **6**.

### Final Answer
The number of occupied subshells in Cr³⁺ ion is **6**.

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