A metallic ion X2+ with an inert gas structure contains 18 electrons. How many protons are there in this ion?
20
18
16
2
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They are correct the answer is 20...let me explain
If the metallic ion X2+ has an inert gas structure, it means that it has a noble gas electron configuration.
Since it contains 18 electrons, which is the number of electrons in the noble gas Argon (Ar), we can assume that the electron configuration of X2+ is [Ar].
The symbol Ar represents 1s2 2s2 2p6 3s2 3p6.
To determine the number of protons in X2+, we need to figure out the atomic number of the element X.
We can do this since the atomic number is the number of protons in the element.
Looking at the electron configuration of Ar, we see that the last filled shell is the third shell. So its atomic number is 18.
However, X2+ has two fewer electrons, so it must have two more protons than Ar.
Therefore, the number of protons in X2+ is 20.
proton number is fixed, what determines the change in charge is decrease or increase in electron number
The given ion is X²⁺, which means it has lost two electrons from its neutral atom.
The problem states that this ion has 18 electrons. So, the neutral atom (before losing two electrons) must have had:
18 + 2 = 20 \text{ electrons}
Since the number of protons in a neutral atom is equal to the number of electrons, the neutral atom had 20 protons.
Thus, the correct answer is:
A. 20
The answer us correct and pls stop extracting formulars that do not exist its confusing 
@darkypearl have seen a formulae like this . E=P-C .where e =electron p= proton and c= charge the answer is totally correct dear
its absolutely wrng d ans s stil 18.
when an element is carrying charges eg
AL3+,having 27 as its mass no and 13 as its atomic no, den d no of proton remains d same as d atomic no 13.
d no of electron is atomic no-charge(3+) 13-3=10.
d no of neutron wil b mass no-atomic no 23-13=14
always use this formulae if u will get confused e=p-c
as u use an instance Al^3+ . no of charge =3 . atomic no is same as proton number which is=13 . so see d formulae e=p-c . e=13-3 . =10. no of neutron is mass no - atomic or proton no 27-13 = 14 . so back to the question . charge =2 electron =18 our formulae
e=p-c . we are looking for p . so p =e+c. p=18+2 .so p=20 QED.
please stop confusing others protons and electrons are equal ,the answer is 18 P=E
the correct answer is 18, becos when there is a positive charge pn an element, it means it has lost that amount of electronds. like this 2+ means it has lost two electrons so i think it should be 20-2=18. my own opinion ooo guys
