Jerusalem is the source of most of the world’s problems. It’s been an open-air madhouse for millenia.

Jerusalem has the Al-Aqsa Mosque is a holy place for Muslims as well. There no way Iran would nuke that. If they had the capabilities they would probably nuke Tel Aviv instead.

Lots of things would happen, but the specifics wouldn’t much matter because there’d be no-one left to tell the tale afterwards.

Depending on where you live, you will need different levels of radiation shielding because of the spread of radioactive materials through water and atmosphere. From consuming basic anti-rad supplements like calcium and iodine containing tablets to finding a good shelter and protective gear from a radioactive rain.

Go take your meds and shut up.

Iran would get glassed