Compsre the bond lengths of : N-N, O-O, C-C and F-F single bonds. Please give a proper explanation for each bond length!

In chemistry there is nothing like always.You have to see any element characteristics than decide its property. the case you are asking about

1)Noteworthy exceptions are single bonds between the period 2 atoms of groups 15, 16, and 17 (i.e., N, O, F), which are unusually weak compared with single bonds between their larger congeners. It is likely that the N–N, O–O, and F–F single bonds are weaker than might be expected due to strong repulsive interactions between lone pairs of electrons on adjacent atoms

2)N-N>F-F ,in F there are greater number of lone pairs than in N so it experiences strong repulsion between its electrons that make it vulnerable to be broken

3)F-F>O-O it's so because F atom is very small that enables strong electrostatic attraction between nucleus and electrons

Bond Lengths

C-C = 1.54 A

O- O = 1.48A

N-N = 1.47 A