Which of the following states that properties of elements are a periodic function of their atomic number''?
A) Dobereiner's triads
B) Modern periodic law
C) Newlands's law of octaves
D) Mendeleev's periodic law

Options

A. Dobereiner's triads
B. Modern periodic law
C. Newlands's law of octaves
D. Mendeleev's periodic law

Answer

To solve the question "Which of the following states that properties of elements are a periodic function of their atomic number?" we need to analyze the options provided and understand the contributions of different scientists to the periodic table.

### Step-by-Step Solution:

1. **Understanding the Options**:
- **A) Dobereiner's triads**: This law states that groups of three elements can be arranged such that the atomic mass of the middle element is approximately the average of the other two. It does not relate to atomic number.
- **B) Modern periodic law**: This law states that the properties of elements are a periodic function of their atomic number. This means that when elements are arranged by increasing atomic number, their properties show a recurring pattern.
- **C) Newlands's law of octaves**: This law suggests that every eighth element has similar properties, based on atomic mass rather than atomic number.
- **D) Mendeleev's periodic law**: Mendeleev's law states that the properties of elements are a periodic function of their atomic mass, not atomic number.

2. **Identifying the Correct Answer**:
- From the analysis, we can see that the only option that states properties of elements are a periodic function of their atomic number is **B) Modern periodic law**.

3. **Conclusion**:
- Therefore, the correct answer to the question is **B) Modern periodic law**.