Question

Choose the correct reason for the following statement.
"In the modern periodic table, nitrogen is placed just before oxygen in the second period."

• A. Oxygen has smaller atomic radius than nitrogen.
• B. Oxygen is more electronegative than nitrogen.
• C. Oxygen has one more proton in its nucleus than nitrogen.
• D. The given statement is false.

Answer 1

The correct option is C Oxygen has one more proton in its nucleus than nitrogen.

Oxygen has smaller atomic radius and is more electronegative than nitrogen. Although these reasons are correct, they will not be considered while deciding the placement of elements in the periodic table. Elements are arranged in the modern periodic table on the basis of increasing atomic number.

An atomic number is the number of protons present in the nucleus of an atom. Nitrogen has seven protons whereas oxygen has eight. Hence, nitrogen is placed just before oxygen.