The correct answer is B. Both Newlands and Mendeleev arranged elements according to their atomic masses, but only Mendeleev used chemical properties as well.
Explanation:
Both John Newlands and Dmitri Mendeleev were relevant chemists, mainly known for designing the period table, which organized chemical elements. In the case of Newlands, he designed his period table around 1865 by organizing the known elements based on the atomic masses of elements (number of protons and neutrons); also, he divided elements into groups.
On the other hand, Mendeleev designed his periodic table around 1869; in this, elements were also arranged by their atomic masses, but Mendeleev considered the properties of each element such as electronegativity, which implied some minor changes in order, as well as leaving some spaces for elements that had not been discovered, but that Mendelev could predict. Thus, the option that compares the organization in both periodic tables is B.
