State modern periodic law of classification of elements.

Explanation

### Step-by-Step Solution:

1. **Understanding the Modern Periodic Law**: The modern periodic law is a principle that helps in the classification of elements based on their atomic structure.

2. **State the Law**: The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.

3. **Proponent of the Law**: This law was proposed by Henry Moseley, who conducted experiments that led to the realization that atomic number, rather than atomic mass, is the more accurate basis for the organization of the periodic table.

...