Question

Which of the properties of an element is a whole number?
A) Atomic Mass
B) Atomic Number
C) Atomic Radius
D) Atomic Volume

Answer 1

Atomic Number is termed as the no. of protons or neutrons present in the atom and atomic Mass is the mass of whole atom which is generally the total mass of the nucleus of the atom i.e., the protons and neutrons.

Complete answer:
A) Atomic Mass is the average mass of the atoms of an element which is measured in the atomic mass unit, known as amu (also known as Daltons(D)). The atomic mass is the average weight of all the isotopes of the element found, in which the mass of each isotope is multiplied depending on the abundance of that particular isotope. Hence the atomic mass is never a whole number. For example, the atomic mass of Hydrogen atoms is $1.008\mu$. Option A is incorrect.
B) Atomic Number is simply the total number of protons/ electrons present in an atom. We are counting whole objects here. Hence the atomic number is always a whole number. Atomic numbers are also whole numbers due to the presence of isotopes which have the same atomic number.
Hence option B is correct.
C) Atomic radius the distance between the centre of the nucleus and the electron present in the outermost shell of an atom. Atomic radius is also known as the half of the distance between identical nuclei of identical atoms bonded together. The atomic radius is measured in Armstrong’s or picometers. Example: The atomic radius of chlorine is 0.175 nm. Hence option C is incorrect.
D) Atomic volume is the volume occupied by one mole of an atom of the element in solid state. It is also known as equivalent, specific or molecular volume. It is given in the units of $c{m^3}$ . One mole of any element occupies a volume of 22.4 L which is not a whole number. Option D is incorrect.

Hence option B is correct.

Note:
The atomic volume of any element can be found out by using the formula $V = \dfrac{4}{3}\pi {r^3}$
Where r is the atomic radius ( in cm/pm/nm) and V is volume ( in $c{m^3},p{m^3},n{m^3}$).