I didn't know how to solve this problem.

also, what does pm stand for?

QuoteI didn't know how to solve this problem.

Ionic radius is the radius of ion and in ionic bond cations and anions are in touch with each other and then we need to calculate the distance between the nuclei of ions. It is a hypothetical question just to make you understand how to calculate the distance of separation of nuclei in ionic attractions. Here they have taken the same size of K⁺ and I^-.This is not correct as I^- is more bigger in size than K⁺.
You need to add size radius of K⁺ and I^-

Quote from: Aditi on May 26, 2024, 05:56:05 PMalso, what does pm stand for?

pm is picometer - unit of length.
1pm = 10^-12 m