Which of the following pair of elements follows Newland’s octave rule -

Options

A. Ne, Ar
B. C, N
C. Na, K
D. P, S

Answer

To determine which pair of elements follows Newland’s octave rule, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Newland's Octave Rule**: Newland's octave rule states that when elements are arranged in order of increasing atomic weight, every eighth element has similar properties. This means that if we list elements in order of their atomic weights, the first element will have properties similar to the ninth, the second to the tenth, and so forth.

2. **List the Elements**: We need to identify the pair of elements from the given options. For this example, we will consider the elements:
- Lithium (Li)
- Beryllium (Be)
- Boron (B)
- Carbon (C)
- Nitrogen (N)
- Oxygen (O)
- Fluorine (F)
- Sodium (Na)
- Magnesium (Mg)
- Aluminium (Al)
- Silicon (Si)
- Phosphorus (P)
- Sulfur (S)
- Chlorine (Cl)
- Potassium (K)
- Calcium (Ca)

3. **Count the Elements**: We will count the elements starting from Lithium to see if any pair matches the octave rule.

4. **Identify the Pair**:
- Start counting from Sodium (Na):
- 1. Sodium (Na)
- 2. Magnesium (Mg)
- 3. Aluminium (Al)
- 4. Silicon (Si)
- 5. Phosphorus (P)
- 6. Sulfur (S)
- 7. Chlorine (Cl)
- 8. Potassium (K)
- Here, Sodium (Na) and Potassium (K) are the 1st and 8th elements respectively.

5. **Conclusion**: Since Sodium and Potassium are the 1st and 8th elements in this sequence, they follow Newland's octave rule.

### Final Answer:
The pair of elements that follows Newland’s octave rule is Sodium (Na) and Potassium (K).

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