If element x has 98 protons, how many electrons does it have?

It will have 98 number of electrons because the number of protons are equals to the number of electrons unless element x has isomers. if it has isomers then only it will have a different electron number but mind it the proton number will remain the same. note: if the proton number changes the whole element changes. 

Outermost (valence) electrons