Number of electrons present in the 3d sub-shell of an element having atomic number 37 is :

Options

A. 7
B. 5
C. 9
D. 3

Explanation

To determine the number of electrons present in the 3d sub-shell of an element with atomic number 37, we will follow these steps:

### Step 1: Identify the Element
The atomic number 37 corresponds to the element Rubidium (Rb).

### Step 2: Write the Electronic Configuration
We need to write the electronic configuration for Rubidium. The electronic configuration is determined by filling the orbitals in order of increasing energy levels according to the Aufbau principle.

1. The first two electrons fill the 1s sub-shell: **1s²**
2. The next two electrons fill the 2s sub-shell: **2s²**
3. The next six electrons fill the 2p sub-shell: **2p⁶**
4. The next two electrons fill the 3s sub-shell: **3s²**
5. The next six electrons fill the 3p sub-shell: **3p⁶**
6. The next two electrons fill the 4s sub-shell: **4s²**
7. The next ten electrons fill the 3d sub-shell: **3d¹⁰**

So, the electronic configuration of Rubidium (atomic number 37) can be written as:
\[ \text{Rb: } 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ \]

### Step 3: Count the Electrons in the 3d Sub-shell
From the electronic configuration, we can see that the 3d sub-shell contains **10 electrons**.

### Final Answer
The number of electrons present in the 3d sub-shell of an element having atomic number 37 is **10**.

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