If the atomic number of an element X is 17, then what will be the atomic number of the element lying in the same group as that of X but in the fifth period?

Options

A. 25
B. 33
C. 35
D. 53

Answer

To solve the problem, we need to identify the atomic number of the element that lies in the same group as element X (with atomic number 17) but in the fifth period.

### Step-by-Step Solution:

1. **Identify Element X**:
- The atomic number of element X is 17.
- The element with atomic number 17 is Chlorine (Cl).

2. **Determine the Group of Chlorine**:
- Chlorine is located in Group 17 of the periodic table, which is also known as the halogen group.

3. **Identify the Periods**:
- The question asks for the element in the same group (Group 17) but in the fifth period.
- The periods in the periodic table are numbered from 1 to 7, with the first period containing the first two elements (H and He), the second period containing elements Li to Ne, and so on.

4. **Locate the Fifth Period Elements in Group 17**:
- The elements in Group 17 (halogens) are:
- Period 2: Fluorine (F) - Atomic number 9
- Period 3: Chlorine (Cl) - Atomic number 17
- Period 4: Bromine (Br) - Atomic number 35
- Period 5: Iodine (I) - Atomic number 53
- Period 6: Astatine (At) - Atomic number 85

5. **Find the Atomic Number of Iodine**:
- The element in the fifth period of Group 17 is Iodine (I), which has an atomic number of 53.

### Final Answer:
The atomic number of the element lying in the same group as element X (atomic number 17) but in the fifth period is **53** (Iodine).

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