Question

1. what do periods (rows) on the periodic table correspond to?

a. a specific number of valence electrons
b. metals, nonmetals, metalloids
c. energy levels of electrons
d. solids, liquids, and gases

Explanation:

• Option A: A specific number of valence electrons corresponds to groups (columns) in the periodic table, not periods (rows).
• Option B: Metals, non - metals, and metalloids are classifications based on physical and chemical properties, not directly related to periods.
• Option C: In the periodic table, elements in the same period (row) have their outermost electrons in the same principal energy level. For example, elements in period 2 have their valence electrons in the second energy level.
• Option D: Solids, liquids, and gases are states of matter, which are not what periods on the periodic table correspond to.

Answer:

C. energy levels of electrons