Question

What is the element with the symbol $Ar$?
A) Aluminium
B) Argon
C) Potassium
D) Neon

Answer 1

It is easy to find the atomic symbol of an element as many of the elements have its own unique atomic symbol starting with its initials. Plus, this particular element belongs to the inert gases group of the periodic table.

Complete step by step answer:
Option A) this is an incorrect option as Aluminium is an element having atomic symbol $Al$ with an atomic number $13$.
We have to know that the electronic configuration of $Al$ is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}$
Option C) this is a correct option as Argon is an element which has an atomic symbol $Ar$ with an atomic number $18$.
Electronic configuration of $Ar$ is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}$
Argon belongs to the group $18$ i.e. noble gas which can also show somewhat properties of inert gas or rare elements thus they are called as inert elements also.
The elements belonging to group $18$ have a stable electronic configuration that means they have filled octet.
Option C) this is an incorrect option as Potassium is an element having atomic symbol $K$ with an atomic number $19$
Electronic configuration of $K$ is $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}$
Potassium belongs to group 1 i.e. Alkali metal is a metal which on losing one electron attains a stable noble gas configuration.
Option D) this is an incorrect option as Neon is an element having atomic symbol $Ne$ with an atomic number $10$ .
It belongs to noble gases i.e. group $18$ it comes above argon in periodic table.
Electronic configuration of $Ne$: $1{s^2}2{s^2}2{p^6}$.

Hence, the correct answer is, ‘Option B’.

Note: The elements belonging to the group $18$ sometimes show inert or rare element properties thus they are also known as rare or inert elements instead of noble gases. They have a stable electronic configuration as the element has a complete octet.