What is the name of the compound with the formula crso4?

Chromium (II) sulfate

this is an ionic compound of a metal and a polyatomic ion.

chromium is a metal that can form more than one type of cation. In this case, the polyatomic ion name is sulfate and it has 2 negative charges. Then Cr has to have 2 positive charges.

then write the name of the metal followed by the charge of the ion between parenthesis and in roman numbers followed by the name of the polyatomic ion.