Can you determine which of two unknown elements has the larger radius if the only known information is that the atomic number of one of the elements is 20 greater than the other? explain.

Yes you can
You can determine that the element with the atomic number that is 20 greater will be bigger because when an element is bigger, it will have more particles (electrons, protons, and neutrons) which means that the atom will get bigger which will cause it to have a bigger radius

Its a hope this