The oxidation number of the underlined atom in the following species is wrongly matched

(1) HAuCl4⇒(+1)+x+4(−1)=0                                  x=+3(2) Cu2O ⇒ 2(+1) + x = 0                                  x = –2(3) ClO3- ⇒ x + 3 (–2) = –1                                      x = +5(4) K2Cr2O7 ⇒ 2(+1) + 2x + 7(–2) = 0                                                   x = +6