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Which one of the following is the most fundamental characteristic of a

June 1, 2025 by rawan239

Which one of the following is the most fundamental characteristic of an element ?

Melting point

Atomic number

Colour

Atomic weight

This question was previously asked in

UPSC NDA-2 – 2020

Download PDF Attempt Online

The correct answer is (B) Atomic number. The atomic number (Z) of an element is defined as the number of protons in the nucleus of an atom of that element. This number is unique to each element and determines its fundamental chemical identity.

The atomic number is the defining characteristic of an element, determining its position in the periodic table and its chemical properties.

Melting point and color are physical properties that can vary depending on conditions or even within different forms (allotropes) of the same element. Atomic weight (more precisely, relative atomic mass) is the weighted average mass of isotopes of an element and is determined by the number of protons and neutrons, but the identity is fixed by the number of protons alone.

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