Which of the following the molecule (s) has/have back bonding ?

Which of the following molecule is planar due to back bonding

Which of the following molecule is planar due to back bonding

Which of the following molecules has (have) a triple bond

Which of the following molecule has no dative bond?

Which of the following molecule has no dative bond?

Which of the following complexes or molecules has/ have N-N bond length greater than that in free N_(2) molecule?

Which of the following molecule has as O-O bonds?

Which one of the following molecules has a coordinate bond