Question

X^ (3- ) is iso electronic with argon if the number of electrons and neutrons are same then mass number of x is?

Answer 1

Iso electronic means that the elements have same number of electrons.

thus it has 18+3=21 electrons. we know,no. of protons=electrons

thus no of protons=21.

since no of electrons=neutrons=21,

mass number=21+21=42

hope this helps!

Answer 2

Answer:

30 Is the mass number.

Explanation:

x an unknow value, if it gains more 3 electrons it will be the isoelectronic to argon.

Isoelectronic means same no of electrons in any two elements are called isoelectronic species.

so, if argon and X³- isoelectronic they have same no of electrons...

And, the number of electrons and neutrons are same but not for X³- for X they are just giving clue(X³- is isoelectronic with argon) to know what is the no of electrons(atomic number) of X

then 18(argon electrons)-3 =15 so electrons are 15 and neutrons are also same.

Then no electrons= No of protons

15= protons

Mass number= no of protons+no of neutrons

so no of neutrons is 15 then,

15+15=30

So the mass number of X³- Is 30.

Thank you, I hope this is helpful to you.