It each orbital can hold a maximum of three electrons, the number of elements in 9th period of periodic table (long form) are:

Options

A. 48
B. 162
C. 50
D. 75

Explanation

To determine the number of elements in the 9th period of the periodic table, assuming each orbital can hold a maximum of three electrons, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Subshells in the 9th Period:**
The 9th period will include the following subshells:
- s subshell (1 orbital)
- p subshell (3 orbitals)
- d subshell (5 orbitals)
- f subshell (7 orbitals)
- g subshell (9 orbitals)

2. **Count the Total Number of Orbitals:**
Now, let's add the number of orbitals from each subshell:
- s: 1 orbital
- p: 3 orbitals
- d: 5 orbitals
- f: 7 orbitals
- g: 9 orbitals

Total orbitals = 1 + 3 + 5 + 7 + 9 = 25 orbitals

3. **Calculate the Maximum Number of Electrons:**
Since each orbital can hold a maximum of 3 electrons, we can calculate the total number of electrons that can occupy these orbitals:
\[ \text{Maximum number of electrons} = \text{Total orbitals} \times 3 = 25 \times 3 = 75 \text{ electrons} \]

4. **Determine the Number of Elements:**
Each unique electron configuration corresponds to a unique element. Therefore, the maximum number of elements that can be accommodated in the 9th period is equal to the maximum number of electrons:
\[ \text{Number of elements in the 9th period} = 75 \]

### Final Answer:
The number of elements in the 9th period of the periodic table is **75**.

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