Question: Name the vacator for Failure to elect
SQL: SELECT "Vacator" FROM "1-225205-3" WHERE "Reason for change" = 'Failure to elect';

Question: Name the state class for  Iowa admitted to the Union December 28, 1846
SQL: SELECT "State (class)" FROM "1-225205-3" WHERE "Reason for change" = 'Iowa admitted to the Union December 28, 1846';