Question

${}^{{}^{\prime }}{X}_{}^{{}^{\prime }}$ is an element present in the modern periodic table. If $X^{3-}$ ion has $15$ protons, then the number of electrons present in $X^{3+}$ ion will be ______.

Answer 1

Answer: 12

The number of protons, neutrons, and electrons in an atom can be determined from a set of simple rules. The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons.
$X^{3-}$ ion has $15$ protons. So, atomic number of $X$ is $15$
$\Rightarrow X$ has $15$ protons and $15$ electrons.
$\therefore X^{3+}$ ion has $15-3=12$ electrons