Question 6

Elements in the same row are arranged from left to right by an increasing number of protons in an atom's nucleus.

In the periodic table, elements are organized in rows known as periods, where each successive element has one more proton than the element before it. This arrangement reflects the increasing atomic number of the elements from left to right.

A) an increasing number of neutrons in an atom's nucleus

This option is incorrect because the arrangement of elements in a row on the periodic table is not based on the number of neutrons. While some elements do vary in neutron count (leading to isotopes), this variation does not determine their position in a row.

B) a decreasing number of neutrons in an atom's nucleus

This choice is also incorrect for the same reason as Option A. The periodic table does not arrange elements based on the number of neutrons, and there is no systematic decrease in neutrons across a row.

C) an increasing number of protons in an atom's nucleus

This is the correct answer. Each element in a row of the periodic table has an atomic number that corresponds to the number of protons in its nucleus, which increases sequentially from left to right.

D) a decreasing number of protons in an atom's nucleus

This option is incorrect because the arrangement of elements does not involve a decrease in protons. Instead, the atomic number, which indicates the number of protons, increases as you move from left to right in a row.

Conclusion

The correct answer is C, as the periodic table is structured based on the increasing number of protons, which directly corresponds to the atomic number of each element. Options A, B, and D fail to recognize the fundamental principle of atomic structure that governs the arrangement of the periodic table.