Question

What are the correct symbol for an isotope of iodine with $53$ protons and $78$ neutrons $?$

Answer 1

Hint : Isotopes are variations of a specific compound component that vary in neutron number, and therefore in nucleon number. All isotopes of a given component have a similar number of protons however various quantities of neutrons in each atom. The number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral atom.

Complete Step By Step Answer:
Isotopes are atoms of the very component that contrast in the number of neutrons in their atomic nuclei. All atoms of a similar component have a similar number of protons, which is the atomic number of that element. Be that as it may, on the grounds that various isotopes have various numbers of neutrons, they can contrast in mass number, which is the amount of the protons and neutrons in the nucleus.
Isotope notation, otherwise called atomic notation, is significant on the grounds that it permits us to utilize a visual symbol to effortlessly decide an isotope's mass number, nuclear number, and to decide the number of neutrons and protons in the nucleus without utilizing a ton of words.
${_Z^A}X$
Here, $X$is the chemical symbol for the element
$Z$is the atomic number of the element
And, $A$is the mass number of the element.
So, the correct symbol for an isotope of iodine is
${^{131}_{53}}I$.

Note :
There are $37$ known isotopes of iodine, all go through radioactive decay with the exception of $1271$, which is steady. Iodine is subsequently a monoisotopic element. Its longest-lived radioactive isotope, $1291$, has a half-existence of $15.7$million years, which is unreasonably short for it to exist as an early stage nuclide.