Linear species among the following is

Number of electron pairs(EP)=V+M-C+A2; V=Group number of central atom; M=-H, -X, -OH....monovalent groups attached to central atom ; C=Charge of cation ; A=Charge of anion ; V=2,3,4,5,6,7,8 respectively for 2nd , 13th, 14th,15th, 16th,  17th, 18th group elements ; Number electron pairs, EP(according to VSEPR theory)=8+2-0+02=5;                                                              Number bond pairs, BP(according to VSEPR theory)=Number of atoms directly attached to central atom;                                                                                                   =2 (in XeF2) ; Number lone pairs on central atom(LP)=EP-BP ;                                                                           =5- 2=3 (in XeF2) ; XeF2=2 bp +3 lp on central atom......linear ;