What is the correct sequence in which the following law was given?

1. Newland's law of octaves

2. Law of triads.

3. Modern periodic table.

4. Mendeleev's periodic table.

The correct option is C

2-1-4-3

At first - Doberneiner's triads, then Newland's law of octaves and further Mendeleev's periodic table and then modern periodic table. Modern periodic table is the periodic table which we follow now. It is arranged on the basis of the atomic number of elements.
Therefore, 2-1-4-3 is the correct answer.