The position of an element in the Periodic Table is determined by

 The position of an element in the Periodic Table is determined by

A. its atomic radius.

B. its density.

C. its relative atomic mass.

D. the number of protons in its atom.

E. the number of neutrons in its atom.

The correct answer is D. the number of protons in it's atom

Explanation:

The position of an element in the periodic table is determined by the number of protons in its atom, which is also called the atomic number. Each element in the periodic table has a unique atomic number which corresponds to the number of protons in the nucleus of its atom. This makes Option D the correct answer.

Atomic radius of Option A is a measure of the size of an atom, but it does not determine an element's position in the periodic table.

An element's density of Option B do not determine the position of an element in a periodic table.

The relative atomic mass of Option C do not determine the position of an element in a periodic table.

The number of neutrons of Option E varies among isotopes of the same element and does not determine the position of an element in the periodic table.

Take note that the periodic table is an arrangement of elements in increasing order of their atomic number, starting from Hydrogen with an atomic number of 1 to elements with higher atomic numbers. 

Each horizontal row in the periodic table is called a period while each vertical column is called a group. The elements in the same group have the same number of outermost electrons and similar chemical properties.

SOURCE: NECO CHEMISTRY 2001 QUESTION 29