Question

Which property of an element is always a whole number?

• A. Atomic weight
• B. Atomic number
• C. Atomic volume
• D. All of these

Answer 1

The correct option is B

Atomic number

Explanation for correct option

(B)Atomic number

Atomic number

• The number of protons present in the nucleus is equal to the atomic number.
• For example, the atomic number of magnesium is $12$.
• The atomic number of an element is always a whole number.
• The atomic number is represented as Z.
• The formula for atomic number is as follows:-

$\text{Atomic number}\left(\text{Z}\right)\text{= number of protons in the nucleus of an atom = number of electrons in a neutral atom}$.

Explanation for incorrect option

(A)

• The mass of one atom of an element is called the atomic weight.
• For example, the atomic weight of helium is $4.002602$.
• So, the atomic weight is not always a whole number.

(C)

• Atomic volume is the result of dividing an element's atomic weight by its specific gravity.
• Atomic volume is not always a whole number.
• Hence, options (A), (C), (D) are incorrect.

Hence, option (B) is correct. An atomic number is always a whole number.