Which is a true statement about Dmitri Mendeleev?

A. Mendeleev created the periodic table in the 1860s.

B. Mendeleev grouped the known elements into four categories: metals, nonmetals, gases, and earths.

C. Mendeleev identified the first 17 elements of the periodic table.

D. Mendeleev organized the elements of the periodic table in the order of decreasing mass.

Answer: The correct answer is option (A).

Explanation:

Dmitri Mendeleev published periodic table in 1869. In his periodic table he arranged the elements in the increasing order of their atomic mass. His periodic table consist total 63 elements. He grouped the element on the basis of similarity of chemical and physical properties of the elements.

Hence, the correct answer is option (A)