Question

The number of nucleons in the isotope of an atom ${X^m}$ are_________.
(A) $m$
(B) z
(C) $m + z$
(D) $m - z$

Answer 1

Hint: first of all we need to understand the term nucleons, that is the total number of neutrons and protons which is its atomic mass of an atom. Also consider identifying how an element is represented in chemistry.

Complete step by step solution:
Nucleon is a proton or a neutron. When we say about the Nucleon number, that is the mass number of an atom.
The number of nucleons in a nucleus defines an isotope’s mass number.
Mass number is the sum of protons and neutrons present in the nucleus.
Here, For ${X^m}$, we see the atomic number is $7$ and mass is $m$. So the number of nucleons in the isotope of an atom ${X^m} $are $m$.

So, the correct option is (A).

Additional information:
Atoms are the fundamental building blocks of all matter and are composed of protons, neutrons, and electrons. Because atoms are electrically neutral, the number of positively charged protons must equal to the number of negatively charged electrons. Since neutrons do not affect the charge, the number neutrons is not dependent on the number of protons and will vary even among atoms of the same element.
Atomic Number: The atomic number (represented by the letter $z$) of an element is the number of photons in the nucleus of each of that element.
Mass Number: Experimental data showed that the vast majority of the mass of an atom is concentrated in its nucleus, which is composed of protons and neutrons. The mass number is defined as the total number of protons and neutrons in an atom.

Note: Now, in the atom given here , X is represented as the symbol of the elements. the atomic mass of the atom is given in the left hand side in subscript given 7 and its atomic number is represented in the right hand side in superscript by m.