Which one of the following species can exist

In option (1), (2), and (4) bond order is zero. They cannot existN2−2 can existN2−2 ......KK (σ2s)2(σ2s*)2 σ2pZ2 (π2px)2(π2py)2(π2px*)1(π2Py*)1B.O = 10-62 = 2;