Fill-in-the blank.  Make sure to include the plus and negati…

Fill-in-the blank.  Make sure to include the plus and negative signs.  Do not write spaces.  (Example: If the answer is positive four enter +4 not + 4).  The chromium atom in K2CrO4 has an oxidation number of [1].  The carbon atom in CO has an oxidation number of [2] The oxidation number of hydrogen in H2 is [3].