The correct order of increasing C-O bond length of CO, CO2−3, CO2 is
B.O. in CO i.e., :−C=+O: is 3, that of O=C=O is 2 while that of CO2−3 ion is 1.33. since the bond length increases as the bond order decreases i.e. CO< CO2< CO2−3. Thus option(d) is correct.