Question

When looking at periods, which of the following are increasing?

Reactivity
Atomic Mass
Energy Level
None

Answer 1

Energy level

Step-by-step explanation:

Periods in the periodic table are arranged in rows. Each row indicates a new period. For example, period 1 starts at the top and consist of only two elements, Hydrogen (H) and Helium (He).

The periods indicate the highest energy level of the elements that fall in the same row. So as the period increases, the energy level increases.