Question

the vertical (top to bottom) parts of the periodic table are called \groups\ or ____.
a periods
b families
c rows
the center section of the period table is classified into ____ elements.
a transition
b noble

Explanation:

1. For the first question: Vertical columns (top to bottom) on the periodic table are called groups, and they are also commonly referred to as families because elements in the same group have similar chemical properties. Periods/rows are the horizontal (left to right) sections of the table.
2. For the second question: The center section of the periodic table contains transition elements. Noble elements are located in the far right column of the table.

Answer:

1. B. families
2. A. transition