We both have 10 neutrons in our nuclei. what are we?

The nuclei having 10 neutrons are fluorine and neon

Explanation:

Isotones are defined as the chemical species of different elements which have same number of neutrons.

Atomic number is defined as the number of protons or electrons that are present in a neutral atom.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

The chemical elements that have 10 neutrons in them are Fluorine and Neon.

Atomic number = 9

Mass number = 19

Number of neutrons = 19 - 9 = 10

Atomic number = 10

Mass number = 20

Number of neutrons = 20 - 10 = 10

Hence, the nuclei having 10 neutrons are fluorine and neon