The element with atomic number 9 resembles in properties with the element having atomic number

Options

A. 19
B. 17
C. 36
D. 27

Explanation

To solve the question about which element with atomic number 9 resembles in properties with another element, we can follow these steps:

### Step 1: Identify the element with atomic number 9
The element with atomic number 9 is Fluorine (F).

### Step 2: Determine the valence electrons of Fluorine
Fluorine has the electronic configuration of 1s² 2s² 2p⁵. The valence electrons are those in the outermost shell, which for Fluorine are 2 (from 2s) + 5 (from 2p) = 7 valence electrons.

### Step 3: Identify elements that have the same number of valence electrons
Elements that have similar properties typically belong to the same group in the periodic table and therefore have the same number of valence electrons. We are looking for another element that also has 7 valence electrons.

### Step 4: Check the atomic numbers of the given options
The options provided are atomic numbers 19, 17, 36, and 27. We need to find which of these elements has 7 valence electrons.

- **Atomic number 19**: Potassium (K) - Electronic configuration: 1s² 2s² 2p⁶ 3s¹ (1 valence electron)
- **Atomic number 17**: Chlorine (Cl) - Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁵ (7 valence electrons)
- **Atomic number 36**: Krypton (Kr) - Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ (8 valence electrons)
- **Atomic number 27**: Cobalt (Co) - Electronic configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷ 4s² (2 valence electrons)

### Step 5: Conclusion
From the analysis, Chlorine (Cl) with atomic number 17 has the same number of valence electrons (7) as Fluorine (F). Therefore, the element with atomic number 9 resembles the element with atomic number 17.

### Final Answer
The element with atomic number 9 (Fluorine) resembles in properties with the element having atomic number 17 (Chlorine).

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