Question

question 1 - 20
elements on the periodic table are arranged into vertical columns called groups. which of the following is true of the elements in a group?
elements in a group have the same mass.
elements in a group have the same number of neutrons
elements in a group have similar properties.
elements in a group have the same number of protons.

Explanation:

Elements in a group (vertical column) of the periodic table have similar chemical properties. This is because they have the same number of valence electrons. For example, Group 1 (alkali metals) all have 1 valence electron and are highly reactive.
The mass of elements in a group increases as we go down the group (due to more protons, neutrons, and electrons). The number of neutrons varies (e.g., hydrogen - no neutrons, deuterium - 1 neutron, tritium - 2 neutrons; they are in the same group but different neutrons). The number of protons (atomic number) is unique for each element (e.g., in Group 1, hydrogen has 1 proton, lithium has 3 protons).

Answer:

Elements in a group have similar properties.