Question

Isodiaphers are the atoms of two elements which have the same values of:
a.) p / n
b.) (p – n)
c.) (n – p)
d.) n × p

Answer 1

Isodiaphers are the atoms of two different elements which possess the same nuclide excess. With this idea in mind, try to ascertain which of the given formulae in the options fits the required criteria.

Complete step by step solution:
Let us first define the term isodiaphers to help establish a basis of understanding of the concept before we take a few examples to ensure that you are extremely thorough with the concept.
In nuclear physics and radioactivity, isodiaphers refers to nuclides which have different atomic numbers and mass numbers but the same neutron excess, which is the difference between numbers of neutrons and protons in the nucleus. Therefore, in simpler terms, we can say that two atoms are isodiaphers when the difference between their Mass Number ‘A’ and atomic number ‘Z’ is the same.
For example, let us consider two atoms $T{{h}^{234}}$ and ${{U}^{238}}$
Now, we observe that the Thorium atom in question possesses 90 protons (since its atomic number is 90). Therefore, we can ascertain that it has 144 neutrons (since 234 – 90 = 144). Calculating the nuclide excess of $T{{h}^{234}}$, we obtain n – p = 144 – 90 = 54
Doing the same for the ${{U}^{238}}$ atom.
We observe that the Uranium atom in question possesses 94 protons (since its atomic number is 94). Therefore, we can ascertain that it has 148 neutrons (since 238 – 94 = 144). Calculating the nuclide excess of ${{U}^{238}}$, we obtain n – p = 148 – 94 = 54
Since their nuclide excesses are both the same, we can therefore conclude that these two atoms are isodiaphers.
Thus, the answer to this question is c)

Note: Be very careful not to confuse isodiaphers with isotopes, isobars or isotones as these are all radically different concepts. If you are confused between any of these concepts, then it is advisable to read through nuclear Chemistry one more time to ensure that you make no mistakes in questions like these.