Which of the following has the maximum number of unpaired electrons?

When N₂, the N-N bond distance _____ and when O₂ goes to $$O_2^+$$ the O-O bond distance ___.

Among the following species, identity the isostructural pairs NF₃, $$NO_3^-$$, BF₃, H₃O⁺ , HN₃

The number and type of bonds between two carbon atoms in CaC₂ are: