What will be the order of increasing radius?

[prakhargupta3301]

My answer is A.
Because effective nuclear charge would increase in order Ar<K⁺<Ca²⁺ and radius would be inverse of that.
However, the answer isn't that. Can you just point me?
Also, can you tell me in this question, do we think of the noble gas and the Ca and K ions as single atomic species or diatomic? Because Ar doesn't exist in single form right? So will be compare metallic radius(for metal ions) and Vander Waal's radius(for noble gas) or ionic radius for all three?

 

[Khashishi]

You don't need any concept of effective nuclear charge here. Just use the actual nuclear charge (the atomic number). The higher the nuclear charge, the more tightly it will bind to electrons.

 

[prakhargupta3301]

You don't need any concept of effective nuclear charge here. Just use the actual nuclear charge (the atomic number). The higher the nuclear charge, the more tightly it will bind to electrons.

So I think C?
Am I correct please tell me.

 

[Khashishi]

yes