Question

the elements from this section of the periodic table all belong to the same
a family
b group
c period
d valence
(chart above: 5 b boron 10.811, 6 c carbon 12.0107, 7 n nitrogen 14.00674, 8 o oxygen 15.9994, 9 f fluorine 18.9984032)

Explanation:

In the periodic table, elements in the same row (horizontal) are in the same period, and elements in the same column (vertical) are in the same group/family. The elements B (5), C (6), N (7), O (8), F (9) are in the same horizontal row (row 2), so they belong to the same period. Option A: Family (group) is vertical, so wrong. Option B: Group is vertical, wrong. Option D: Valence relates to electron bonding, not the table's horizontal/vertical grouping here. So the correct answer is C.

Answer:

C. period